We'll know on the 8th. Past performance is no indicator of future performance. (If a huge bug is discovered in the AT&T version late on the evening of the 7th, they won't be shipping anything on the 8th, regardless of the shipping schedule.)
If T-Mobile is already shipping the phones AT&T should do it as well..
Why should T-Mobile be able to disregard the official release date and get the free publicity at the expense of the other carriers...Just ship the phones already since the release date is not binding....
We are talking over a week early....
I'd say no. I think they plan for a day to start shipping, maybe make sure they have plenty of people on hand and stick to that day. I've never seen or heard of them ship earlier than the week of the release. Hoping I'm wrong though.