Totally agree that Apple has made it a pain this year. I am all paid up/paid up to the percentage needed on my 7+ and am ready to trade in. I feel the same way you do, that the delivery date will drop fast. I am curious to hear what other people think on how fast, but my guess is if you don't get your pre-order in in the first 10-15 minutes, you could be waiting a while.
[doublepost=1508847989][/doublepost]
I could be wrong on this, so don't quote me, but the way I understand it is if you are completely paid up on your phone you can use the apple store app to upgrade and what I did last year was pay what I could upfront and setup the monthly payment plan through ATT using the Apple store app.
For me though, I am in a different boat this year, I just paid up to the percentage needed to be eligible to trade in, so I have to go through the ATT website/app to upgrade, unless I decide to pay off my remaining balance in the next few days.