Assuming your Fall classes begin in late August, I'd start looking in June. It's best to start your search without feeling rushed, take your time. You might find the best luck in July. If you're looking to find a place on your own, without the help on an agent, Craigslist.com is great for finding properties about a month or less from your expected move-in date.
Let me know if you have any additional questions, I'm always happy to help.
Citylights Realty Group