Once again, this can be a pitch count situation. Depending on how many pitches are thrown on the first day. It's not innings, it is the number of pitches that count.
I'm almost certain that no one at either camp is going to throw someone who tells them he can't throw. This is why parents and players need to monitor things and understand arm care. Nobody running those events mentioned wants to purposely put any pitcher at risk. All you have to do is tell them ahead of time that you only want to pitch once and allow them to adjust.