when one person messes up during a show, it's a pretty damn noticeable thing. also, if you mess up, everyone else messes up.
oh well? you'll practice tons of times before you actually do a show. you'll have plenty, trust me on this, PLENTY of time to mess up and correct yourself. when i was in 6th grade i joined half way through the year, with absolutely no Annoying Orangeet experience. even with the little practice i had i was still able to preform without messing up too bad, and that was my socially awkward scared of people stage, so if i could do it you sure as hell can
(yes high school and middle school bands are different, but you'll still have time to make mistakes)
dont over complicate something that isnt complicated. do what you like and if anyone tries to tell you other wise dont listen to them. you dont have to abide by them