I usually got there the day before, between 3pm-10pm.
The venues set their own line-up times and procedures. For example, the Palace of Auburn Hills is terrible, they let no one on the property until 2pm the day of and I'm never going there again even if it's the closest, while the United Center is awesome because they allow camping and even open the gates for porta-poty use and the director brought us water and snacks.
The lottery changes things though because on Oct. 24 I showed up at 5:30pm the day of, waited for the GA line to clear, walked right in, found a spot at the back, then asked a lady for wristbands, went into the ellipse five minutes before U2 came on, and ended up with a great view on the side rail towards the back. Other times I've waited over 24 hours and been stuck on the outside rail way over to one side. Twice I got lucky and made it into the ellipse having a great spot in line so got to be on the front rail in the middle.