12-14. BUT it also depends on how big your beginner classes are. They should all be pretty proportionate to what a full band is. So if you have 6 in a 56 person band, where every section is ideal, what do you have in double the band size or triple? What is close to your beginner numbers?

Yes, we would never need a concert band with 18 percussionists and 178 members total, but you (hopefully) get my point.