Originally Posted by
crosvs
Actually, wait, one last follow-up: does it matter when, precisely, I check in then? I.e., should I still always aim to check in at precisely T-24?
This is sort of an open question. Frankly, it probably doesn't matter very much! The arguments for and against checking in early are:
(pro): The waitlist for "battlefield upgrades" is sorted first by premium fare class (Y, then B, then 1Ks on M fares, then everything else), then by status (so a Silver on a B fare trumps a 1K on a Q, but all the non-Y/B/M fares are sorted by status), then by fare class... and
finally by checkin time as a tie-breaker.
So, in the unlikely chance that there is another Gold on exactly the same fare class as you
and there is exactly one upgrade left for the two of you... the one that checks in first gets it.
(con): Since the systems switchover on 3/3/12, it appears that you can still get advance CPU
after T-24... but not if you've checked in. This is not clear; some reports indicate upgrades clearing after checkin, and lots of flights clear no upgrades between T-24 and the gate.
Summary: some people check in early in case of tie-breaker; some check in late in case it improves their chances of CPU at T<24. YMMV