It could work if she's just as busy as you are and understands your schedule. It might be annoying though if she starts nagging that you're not spending enough time with her. I wouldn't do it personally because I don't think I could handle being pulled in two directions like that especially my first year. And i guess that's another thing you should consider... your first year will be the most demanding. Maybe she should move in after you've settled in for a year or a semester. That way you get to get acclimated to your environment and work load on your own before you have to start accomodating your live-in relationship with her. I think that's what you should do. Let her join you later.
Just to offer an opposite response...Considering you will probably have zero time to "hang out" or go on dates or whatever, you might find living together a good way to actually see each other. Even if it is while you are getting ready in the morning, or while you are cooking dinner it is still time spent around each other.I'd just make sure she is very clear on how demanding your 1L will be.