BGR says AT&T is planning for a September launch of the new iPhone during week 3 or 4. They also moved a training from the first week of October because of a "huge announcement". An all hands on deck extends till the the middle of October.
http://www.bgr.com/2012/08/13/iphone-5-release-date-att
According to a trusted AT&T (T) source, the carrier is currently planning to launch Apples (AAPL) next-generation iPhone during the third or fourth week of September, with an all-hands-on-deck policy in place for employees that will extend through to the middle of October. A second AT&T source confirms that a large training event for regional employees has been rescheduled from the first week of October due to a conflict with a huge announcement. Apple is expected to introduce the iPhone 5″ alongside other new iOS devices at a press conference on September 12th.
http://www.bgr.com/2012/08/13/iphone-5-release-date-att