I'm a pretty regular recipient of op-ups (just lucky, I guess), but IME, in clear oversell situations like this, it does not matter if I'm checked in already or not...if they're doing it by status, you'll get it at the gate.

I agree VDB is a decent chance here, but your play on this flight is probably for a better Y seat. My guess is that they're going to clear those last four F seats at the gate, and what you want is the exit row seat of the 1K who's being upgraded. Since this will probably be done at the gate, it again doesn't matter when you check in. But, when you're talking to the GA an hour before the flight about VDB, ask whether you can be put in a seat of someone who's upgraded, rather than the last person to check in (just ask...a non-cranky GA will give it to you by status...you don't want to try to be the last person to check in on an oversold flight).

My advice is to OLCI now, and make your moves at the gate.