It's my experiences that mags in those classes are rarely loaded to capacity. Typically, 6-10 rounds, max. This facilitates the need to reload more often. If the class asks for 4 mags, minimum, then I'd do everything I could to get 4 mags. Given today's situation on availability of mags, they might be understanding, and work with you. But you won't know for sure unless you ask.
EDIT: Now I read the rest of the thread and see my post is unneeded.
Have fun at your class, be prepared to learn a bunch.