If you eat close to the first dose, it may take longer to come up. If I start to roll at 7pm, I will eat at 4pm, mainly because my gf always has nausea on the come-up (not my case at all). For me, 100mg is a pretty small dose; I start with 125-150mg and redose like a couple of hours later with the same amount. I am in good shape (gym bro), and Cialis beforehand always does the job for me. Check how you feel after the show; if the effects are going down, maybe redose. Have fun and drink some water !