Plan to arrive about 20-30 minutes before his show if you want to make sure you will have a seat. His act is located in the lounge, which means tables and booths are occupied by folks having a drink or two and maybe some snacks. Once his show begins any remaining seats fill up pretty quickly. The good news is folks who are only there for drinks/snacks get up and leave during the show, which frees up seats from time to time. We usually arrive early, order some soft drinks and snacks (the natchos are REALLY good at the lounge), then sit back and wait for the fun to begin.
Bob will also usually walk around the lounge before a show begins and chat with the guests there. He'll ask where you're from, who's with your group, whether its your first visit, etc., and then if he can, he'll work it into the show (we told him we were from Virginia, and he sang "Country Roads" which is actually WEST Virginia, but then again there aren't too many songs with the State of Virginia in the lyrics).
Each show usually lasts around an hour or so. I think on weekends he does 2 shows a night.