If it’s like Eat to the Beat (I assume it is), you can arrive at any time prior to the 5:30 performance to get a seat. After the 5:30 performance, the entire theater is emptied and then re-filled. You can go back in, of course, but a line might have formed while the first show is happening. The band I saw at Eat to the Beat had a pretty long line (down past Italy) after the first show but I still was in the front rows of the second section after leaving the first set and joining the line. There’s a lot of room in there and pretty much all of the seats are good, even if not all close. Just don’t sit behind a tree!