You can be 5-10 minutes late for Oga's I think without penalty. Might even be 15 minutes.
Oga's is pretty cool if you've never been but not mind blowing as others have said. The cocktails aren't that tasty (pre-mixed). I'd rather have a cocktail at pretty much any of the DCA or GCH places. But it's cool scenery to check out, and you can get beer instead which they can't mess up obviously!