Option A: Give each student a performance time (Ex. Room 131 Johnny plays at 1:30, Samantha plays at 1:34, Cameron plays at 1:38, Crystal plays at 1:42) and you just have them show up 30 minutes before that time.
Option B: You give a MASS call time for each student assigned to that room, regardless if they are first or last to go in the room. Then they warm up and can go in any sort of order you decide.
I've done Option A for a few years and it has been efficient, but I feel like B might be an even better option to avoid students coming late at the very last second before their assigned playing time and not being able to warm up much.
Thoughts? Or is there an even better option?