When do I request permission to enroll/submit pre-requisite clearance request?

I’m a new student coming to UCLA as part of the Education Abroad Program. I’m planning my courses and all of them have prerequisites, which I believe I have covered at my home university, but since I don’t have a UCLA record I need to submit prerequisite clearance requests for them. When do I do this, before my pass opens on June 30th or after? I’d like to enroll as soon as possible as classes are already starting to fill up. Thanks!

It has to be done before

@10s4life thank you!