Have a Friday flight at 7pm. There's a 3pm flight with some avail, which I'd like to try to get on.
Should I check in for my 7pm flight on nwa.com on Thursday (partly for the bonus miles), or will that make it more difficult to get on the earlier flight if there's room.
Does it change the situation if my silver elite upgrade clears on Thursday?
Thanks.

It doesn't matter if you check-in over the web for your scheduled flight. Just bring your boarding pass and asked to be cleared standby for the 3pm. If there's room - they'll do it at the counter, not the gate.

Well, your second questions is your dilemma -you may clear first on your 7pm flight, but first may not be available for you on the 3pm flight. So it's your call what's more important to you - time or comfort? If F is available for 3pm than they'll clear your in F standby as well. If I were you, I'd expect to be riding the 3pm in coach as a silver.

In a nutshell, the elite upgrade or web check-in has no impact on flying standby. Use flyaow to check the class availability, and then decide on Friday what you want to do. Time vs. comfort.

Thanks for the very detailed response. So if I check in on the web for the 7pm, and get to the airport at 1pm hoping for the 3pm flight, you're saying they'll push me on the 3pm at the counter, right away? What if there's only a few seats left on the flight? Will they confirm me that early, or will they make me sweat it out until a few minutes before boarding?

Agreed about riding in coach for the early flight. ITN shows P9 F5 for my original flight, but P6 F1 for the standby (along with only Y4...)

In my experience it all depends with the agent at the counter. On average though, if your original fare class is available for the standby flight the counter will do it. If there's only a few seats left (this appears in your case with only Y4), they'll make you sweat it out at the gate. It helps that you are an elite. But just keep checking the class availability (flyaow) b/c I imagine more seats will be released as Friday approaches.