Full Disclaimer: This is my first time flying CO as an elite, so be gentle.
I'm flying SFO-IAH on the "redeye" tomorrow night. It's a 757-300 which shows F9 and 16 out of 24 F seats empty. Is it normal for EUA to not have run yet to upgrade people?

Is there any reason to check in as soon as possible or to wait closer to flight time? I don't know if that affects EUA.