We have been waiting for June 2013 on Southwest. They are currently booking through May, so we are on pins and needles. We have not seen anything about the extended schedule on the SW forum, but check daily for our dates.
Sorry I know that does not help you, except that misery loves company?
Southwest posts their information on Travel Tools. It says they are extending through 8/9/13 on 11/19/12 so it may be another few months before they go into September.
I've seen SW release date history posted on these boards, but what about JetBlue? Are their releases so erratic that it's not worth tracking patterns from previous years?
I'd like a little more than the couple days' notice provided by signing up for TrueBlue.
I know there are some compulsive planners who have this tucked away somewhere! Any ideas?