I'd have to think it's early in the AM... but that wouldn't make much sense, considering the order of the last few strips with Hanners and MG.
EDIT: I don't think we've ever seen the blackboard
completely blank; a few of the early strips don't have the board in the background (see
strip 9); the first time we see the blackboard is
strip 29, and there is something written down at the bottom ("If you can afford a Powerbook, you..." is all you can see).