@DiotimaDM IIRC, Psychology courses, except for 400-level ones, usually fill quickly. I have no idea about theatre. I will hopefully take some business courses, but I’m waiting until spring to start because MGMT 303 fills within the first 2 days of fall registration.
I suspect that for your son (and me), earlier vs later orientation/registering won’t matter much. Almost all of the students taking classes within their majors (i.e. not freshmen) will have registered one month prior to the first orientation date.