Originally Posted by lucky9876coins

...The list continues as such, except 500 milers, which can only clear 120 hours out for GS's, 100 hours out for 1K's, 72 hours out for 1P's, 48 hours out for 2P's, 36 hours out for 3P's, and 24 hours out for GM's. If the upgrade does not clear at the window (which is very possible, it's not that you get upgraded if there's a seat available, but rather it's still coming from the same inventory), you can still clear anytime until departure.