I'm in the same boat as you, ordered the same iPhone Pro Max also from T-Mobile. What a mess pre-ordering was/is this year.
- I was online before 8 am EST and couldn't get into the Apple Store app for more than 10-15 mins.
- Once in, Apple couldn't verify my phone line or PIN with T-Mobile.
- I got a reservation ticket # finally from Apple saying T-Mobile was having trouble...
- T-Mobile's website got me to the confirm order step after shipping address & Payment and would just spin and spin.
About 10:40 am I tried Apple Store app again on a whim, this time it took and my order is set for delivery Oct 10 - 17 also by Postal Service (it says).
I guess deliver 3-4 weeks late isn't so bad given all the issues. I'll be traveling on Sept 16 anyway.
I highly doubt Apple is going to ship the new iPhone by Postal Service. If so I'll never get it!š
I'm sure it will update to UPS at some point. What a mess pre-order was this year!
Shout out to people I recognize from previous pre-order threads.