I just graduated from law school.
I would say do it before classes start, then again midway through the semester.
I say this because you may feel overwhelmed during the course of the semester and not get to it.
Even better, get Barbri materials. It'll really help with the first year, and it'll help teach you how to write a law school exam. If I had taken Barbri going into my first year of law school, I'm sure I would have aced everything. Your school library may have the materials. Mine did, but I didn't know how to make good use of them.