Well, it always works for me at THIRTY days. So, I'm leaving Feb 11 - THAT is 30 days from now (not the 12 as posted above - that's why I pointed out Jan has 31 days - I was not trying to be a jerk!) Further, like I said, to the minute! That means if my flight leaves at 5:05 PM CST on Feb 11, I will be able to select at 5:05 PM CST on Jan 12, and not one minute before. Just tried - I can't - I have confidence I can after 5:05!

Computer controlled clock - just like checkin. And it's not 30 days from the first segment of the trip (like upgrades) in question, it's 30 days from the exact flight in question. As an EXP rep told be some time ago, saying 720 HOURS before flight is actually the correct thing to say!