Originally Posted by
Thunderroad
Does it make any difference for my place on the upgrade list if I online check in ASAP?
No.
jamanatu is right on.
is it better or worse to check in early?
Worse. If your upgrade clears and you've already checked in, you'll get whatever seat your assigned and will be unable to change it until you arrive at the airport. OTOH, if you wait and your upgrade clears
before you've checked in, you can just change it online and then check in.