take it in June. With something that's this important and that is time sensitive, it is NOT a good idea to procrastinate.
If you wait until the fall and bomb it, you won't have enough opportunity to retake it. You never know, you could get sick or have a family emergency or something. If something happened, you'd probably have to end up taking a year off school or more.
Which for some people time off between undergrad and law school works (see valkyrie), but for some people that would not have been the best choice (like me).
But then again, make sure law school's something you really want to do
I don't know how many people i've talked to lately that say they're thinking about going to law school, but really have no idea what's involved. So many people are delusional that all lawyers make a ton of money, even starting out, and that's just not true. Plus there are a lot of lawyers on market right now....