Anytime after 8:00 is a safe bet but surely they won't take the stage until the crowd is in their seats. They play Blitzkrieg Bop on the PA before the show and then dim the lights a little, followed by a couple other songs with a sort of "let's go" kind of message to start getting people away from the concession stands and into their seats. I noticed the lights kept getting dimmer and dimmer after 8:00 until they finally started. They waited until that arena was full, which I totally understand.