Thought this thread was dead since it was all about people that must have everything in the first hour it's available.
Anyway, here's my trade in story from Tmob. 64GB white i5, quoted $250 on website when researching, went to $253 by the time I hit Submit on 9/18. The website did not let you apply it directly to a preorder with an EIP, but recommended that you wait until it was all set up from the new phone, then it could be applied to your account later.
My 5 was in pretty good shape, original screen with no damage. Many little marks on the bezel, though. Brand new battery courtesy of Apple's replacement program that popped up recently.
I waited a bit compared to some, received my 6 on 9/22, the Monday after shipping began. Sent the 5 to Tmobile a day or two later. By the end of that week, the online status went to Processing or whatever they called it. Within 2 weeks, it said the phone was accepted, at $253, and it could take up to 3 bill cycles (aka: months) to hit my account. That timeframe is in the Terms, so I already knew that. But, within a week, it was already on my account as a credit. That was around 10/8, last week. I think it was 20 days all told from submission on the site to the credit on my account.
So, really fast and I got the full amount the site claimed. They did have some issues, the cash got applied to my account generically when I wanted it to go as a payment specifically on the EIP. Had to make a phone call about that, and it isn't all done, yet. But my regular payment goes through this week, so it is supposed to all be in the correct places once that happens.