It's funny, because I called the elite line and asked them basically this very question. They said I was on a standby list for first class anyway, since I was inside the 36 hour window and I had not been upgraded. The agent also said that checking in early would not help in my case, because I was already on the list. I called back (of course, who here wouldn't!) and asked the same question, got the same answer, and the fabulous agent (most of them are) also looked at the list and confirmed that I was on it.

Therefore, I'm not sure in the face of that confirmation, and given that I have checked baggage, that there is any real advantage to checking in early.

I wonder of others agree.