Typically:
7:00 Club opens (but if there is a private event, which is not uncommon, could be as late as 9:00).
7:30 - 8:00 First show somewhere in here, I'm rarely there that early. Think it's 7:45 or 7:50, but not 100% sure.
9:20ish Balderdash Cup, best show of the night, begins. Honestly, pays to be there by 9:00, to be "inducted" as a new member first, good way to get into the feel of the place.
12:40 Last show of the night, the Hoopla. Let's out at 1:00, entertainment is done for the night, although main bar remains open. [You specifically mentioned Saturday--on less crowded nights, they will often cancel one of the earlier shows and run the last show of the night closer to 12:05, meaning entertainment done by 12:30.]
1:30 Last Call
2:00 Club closes