I was on an AA flight, but this is the only FT thread I coul find on the topic, so I'll share my experience.

I got to the airport at 5 am on a Wednesday morning. No line whatsoever at the agricultural inspection point, I just walked up and put my bags on the belt. Two people in line at the TSA ID checkpoint, and a few waiting to put their bags through the X-Ray. Apparently they turn on the backscatter machines at 5, because everyone went through the metal detector until the girl in front of me. I opted out, got a patdown, and walked down to the Admirals Club. By this time it was 5:15, but the AC doesn't open until 5:45 am. The first AA flight is at 6:40.

So I would agree with the 45-60 minutes early standard for an early morning flight. If the AC doesn't open until 55 minutes before the first flight, there can't be too many experienced travelers arriving much earlier.