Here is the availability for the iPhone 13 mini, iPhone 13, iPhone 13 Pro, and iPhone 13 Pro Max for the mid-afternoon of October 8th, 2021.
All of Verizon's models have changed to October 29th. T-Mobile's models keep vacillating and the largest number of changes have come with availability through AT&T. 
Changes for the Carriers
AT&T
	- iPhone 13 mini - 256GB - Midnight has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
- iPhone 13 mini - 512GB - Midnight has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
- iPhone 13 - 128GB - Blue has changed from Oct 11 - Oct 12 to Oct 14 - Oct 15
- iPhone 13 Pro - 128GB - Sierra Blue has changed from Oct 22 - Oct 29 to Oct 25 - Nov 01
- iPhone 13 Pro - 1TB - Sierra Blue has changed from Oct 22 - Oct 29 to Oct 25 - Nov 01
- iPhone 13 Pro - 128GB - Silver has changed from Nov 05 - Nov 12 to Nov 08 - Nov 15
- iPhone 13 Pro - 1TB - Silver has changed from Nov 05 - Nov 12 to Nov 08 - Nov 15
- iPhone 13 Pro - 128GB - Gold has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
- iPhone 13 Pro - 128GB - Graphite has changed from Oct 22 - Oct 29 to Oct 25 - Nov 01
- iPhone 13 Pro - 512GB - Graphite has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
- iPhone 13 Pro - 1TB - Graphite has changed from Oct 22 - Oct 29 to unavailable
- iPhone 13 Pro Max - 128GB - Sierra Blue has changed from Nov 05 - Nov 12 to Nov 08 - Nov 15
- iPhone 13 Pro Max - 256GB - Sierra Blue has changed from Oct 18 - Oct 25 to Oct 20 - Oct 27
- iPhone 13 Pro Max - 1TB - Sierra Blue has changed from Oct 22 - Oct 29 to Oct 25 - Nov 01
- iPhone 13 Pro Max - 128GB - Silver has changed from Nov 12 - Nov 19 to Nov 15 - Nov 22
- iPhone 13 Pro Max - 256GB - Silver has changed from Nov 05 - Nov 12 to Nov 08 - Nov 15
- iPhone 13 Pro Max - 512GB - Silver has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
- iPhone 13 Pro Max - 1TB - Silver has changed from Oct 29 - Nov 05 to Oct 25 - Nov 01
- iPhone 13 Pro Max - 128GB - Gold has changed from Nov 05 - Nov 12 to Nov 08 - Nov 15
- iPhone 13 Pro Max - 256GB - Gold has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
- iPhone 13 Pro Max - 1TB - Gold has changed from Nov 05 - Nov 12 to Nov 08 - Nov 15
- iPhone 13 Pro Max - 128GB - Graphite has changed from Oct 22 - Oct 29 to Oct 25 - Nov 01
- iPhone 13 Pro Max - 256GB - Graphite has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
- iPhone 13 Pro Max - 512GB - Graphite has changed from Oct 15 - Oct 22 to Oct 18 - Oct 25
T-Mobile
	- iPhone 13 - 128GB - PRODUCT(RED) has changed from Oct 12 - Oct 18 to Oct 08 - Oct 11
- iPhone 13 - 256GB - PRODUCT(RED) has changed from Oct 12 - Oct 18 to Oct 08 - Oct 11
- iPhone 13 Pro - 512GB - Sierra Blue has changed from Nov 03 - Nov 17 to Oct 08 - Oct 11
- iPhone 13 Pro - 256GB - Gold has changed from Nov 03 - Nov 17 to Oct 08 - Oct 11
- iPhone 13 Pro - 128GB - Graphite has changed from Oct 26 - Nov 09 to Oct 08 - Oct 11
Verizon
	- All model have changed from Oct 22 to Oct 29
	iPhone 13 mini
	
		
			| Sim-Free | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 21 - Oct 26 | Oct 21 - Oct 26 | Oct 21 - Oct 26 | 
		
			| Blue | Oct 21 - Oct 26 | Oct 21 - Oct 26 | Oct 21 - Oct 26 | 
		
			| Midnight | Oct 21 - Oct 26 | Oct 21 - Oct 26 | Oct 21 - Oct 26 | 
		
			| Starlight | Oct 21 - Oct 26 | Oct 21 - Oct 26 | Oct 21 - Oct 26 | 
		
			| PRODUCT(RED) | Oct 21 - Oct 26 | Oct 21 - Oct 26 | Oct 21 - Oct 26 | 
	
	iPhone 13
	
		
			| Sim-Free | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 29 - Nov 3 | Oct 29 - Nov 3 | Oct 29 - Nov 3 | 
		
			| Blue | Oct 29 - Nov 3 | Oct 29 - Nov 3 | Oct 29 - Nov 3 | 
		
			| Midnight | Oct 29 - Nov 3 | Oct 29 - Nov 3 | Oct 29 - Nov 3 | 
		
			| Starlight | Oct 29 - Nov 3 | Oct 29 - Nov 3 | Oct 29 - Nov 3 | 
		
			| PRODUCT(RED) | Oct 29 - Nov 3 | Oct 29 - Nov 3 | Oct 29 - Nov 3 | 
	
	iPhone 13 Pro
	
		
			| Sim-Free | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
		
			| Silver | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
		
			| Gold | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
		
			| Graphite | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
	
	iPhone 13 Pro Max
	
		
			| Sim-Free | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
		
			| Silver | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
		
			| Gold | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
		
			| Graphite | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | Nov 10 - Nov 17 | 
	
	iPhone 13 mini - Carriers
	
		
			| T-Mobile | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 08 - Oct 11 | Oct 08 - Oct 11 | Nov 03 - Nov 17 | 
		
			| Blue | Oct 08 - Oct 11 | Oct 08 - Oct 11 | Nov 03 - Nov 17 | 
		
			| Midnight | Oct 08 - Oct 11 | Oct 08 - Oct 11 | Nov 03 - Nov 17 | 
		
			| Starlight | Oct 08 - Oct 11 | Oct 08 - Oct 11 | Nov 03 - Nov 17 | 
		
			| PRODUCT(RED) | Oct 08 - Oct 11 | Oct 08 - Oct 11 | Nov 03 - Nov 17 | 
	
	
		
			| Verizon | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 29 | Oct 29 | Oct 29 | 
		
			| Blue | Oct 29 | Oct 29 | Oct 29 | 
		
			| Midnight | Oct 29 | Oct 29 | Oct 29 | 
		
			| Starlight | Oct 29 | Oct 29 | Oct 29 | 
		
			| PRODUCT(RED) | Oct 29 | Oct 29 | Oct 29 | 
	
	
		
			| ATT | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
		
			| Blue | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 14 - Oct 15 | 
		
			| Midnight | Oct 12 - Oct 13 | Oct 18 - Oct 25 | Oct 18 - Oct 25 | 
		
			| Starlight | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
		
			| PRODUCT(RED) | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
	
	iPhone 13 - Carriers
	
		
			| T-Mobile | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 12 - Oct 18 | Oct 12 - Oct 18 | Oct 19 - Nov 02 | 
		
			| Blue | Oct 12 - Oct 18 | Oct 12 - Oct 18 | Oct 19 - Nov 02 | 
		
			| Midnight | Oct 12 - Oct 18 | Oct 12 - Oct 18 | Oct 19 - Nov 02 | 
		
			| Starlight | Oct 12 - Oct 18 | Oct 19 - Nov 02 | Oct 19 - Nov 02 | 
		
			| PRODUCT(RED) | Oct 08 - Oct 11 | Oct 08 - Oct 11 | Oct 19 - Nov 02 | 
	
	
		
			| Verizon | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 29 | Oct 29 | Oct 29 | 
		
			| Blue | Oct 29 | Oct 29 | Oct 29 | 
		
			| Midnight | Oct 29 | Oct 29 | Oct 29 | 
		
			| Starlight | Oct 29 | Oct 29 | Oct 29 | 
		
			| PRODUCT(RED) | Oct 29 | Oct 29 | Oct 29 | 
	
	
		
			| ATT | 128GB | 256GB | 512GB | 
	
	
		
			| Pink | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
		
			| Blue | Oct 14 - Oct 15 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
		
			| Midnight | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
		
			| Starlight | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
		
			| PRODUCT(RED) | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | 
	
	iPhone 13 Pro - Carriers
	
		
			| T-Mobile | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Oct 26 - Nov 09 | Nov 03 - Nov 17 | Oct 08 - Oct 11 | Nov 03 - Nov 17 | 
		
			| Silver | Oct 26 - Nov 09 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | 
		
			| Gold | Oct 26 - Nov 09 | Oct 08 - Oct 11 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | 
		
			| Graphite | Oct 08 - Oct 11 | Oct 26 - Nov 09 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | 
	
	
		
			| Verizon | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
		
			| Silver | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
		
			| Gold | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
		
			| Graphite | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
	
	
		
			| ATT | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Oct 25 - Nov 01 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Oct 25 - Nov 01 | 
		
			| Silver | Nov 08 - Nov 15 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Nov 08 - Nov 15 | 
		
			| Gold | Oct 18 - Oct 25 | Oct 12 - Oct 13 | Oct 12 - Oct 13 | Nov 30 - Dec 07 | 
		
			| Graphite | Oct 25 - Nov 01 | Oct 12 - Oct 13 | Oct 18 - Oct 25 | unavailable | 
	
	iPhone 13 Pro Max - Carriers
	
		
			| T-Mobile | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | 
		
			| Silver | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 12 - Dec 03 | 
		
			| Gold | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | 
		
			| Graphite | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | Nov 03 - Nov 17 | 
	
	
		
			| Verizon | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
		
			| Silver | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
		
			| Gold | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
		
			| Graphite | Oct 29 | Oct 29 | Oct 29 | Oct 29 | 
	
	
		
			| ATT | 128GB | 256GB | 512GB | 1TB | 
	
	
		
			| Sierra Blue | Nov 08 - Nov 15 | Oct 20 - Oct 27 | Oct 12 - Oct 13 | Oct 25 - Nov 01 | 
		
			| Silver | Nov 15 - Nov 22 | Nov 08 - Nov 15 | Oct 18 - Oct 25 | Oct 25 - Nov 01 | 
		
			| Gold | Nov 08 - Nov 15 | Oct 18 - Oct 25 | Oct 12 - Oct 13 | Nov 08 - Nov 15 | 
		
			| Graphite | Oct 25 - Nov 01 | Oct 18 - Oct 25 | Oct 18 - Oct 25 | Nov 30 - Dec 07 |