Housing waitlist and leasing an apartment

<p>Unfortunately I'm going to be on the housing waitlist for fall 2011. I looked into off campus housing and found some decent, cheap apartments online. My question is, when should I set up an apartment lease? I might not know how the waitlist pans out until July or later. What if I find out in July that I can't get a dorm, and by then all the apartments are taken? I never leased an apartment before so I'm not sure how this works. Any help is appreciated.</p>