The Verge is reporting that they have spoken with several sources close to Microsoft and Nokia and have confirmed that Nokia is shooting for November 2 as the launch date for the new Lumia 920 on AT&T. Currently, Nokia is working with AT&T running tests so that the phone will be signed off on in time for the planned launch.
This involves AT&T running tests in its labs on the Lumia 920, while Microsoft is still testing the yet unreleased Windows Phone 8 software. The latter is expected to go to RTM sometime next week. It is set to launch October 29, just a few days before the planned launch date for the Lumia 920 by AT&T.
It's important to note that the launch date could be pushed back further into to November if issues arise during testing. While there is probably a little bit of padding built into the launch time frame, a big enough issue could push it back. Just don't expect to the see Lumia 920 before November 2.