For someone with an on call work schedule, when are the best times to avoid the largest crowds?

Depends on what you call early morning. I'm there by 4am and only about 4-6 regulars there. When I leave by 530 though it is filling up quickly with 20 or more.

Early morning, late night

Early mornings, late nights

Usually later at night, or early in the morning!

Are you kidding? It is packed late not, and early mornings.

Late night, early morning

You can see , call for exatly time and day