This is kind of a hit or miss. If you look too soon and find the right place, you'll have to just wait it out. If you start looking too late and can't find anything you like, you are out of luck. I would recommend looking into the neighborhoods and learning where you would/would not like to live and at least narrow that down soon. Then, maybe mid-August, see how many rentals there are in the area. If there are quite a few, you might want to wait until beginning of September, if not, you would want to start in August. But I probably wouldn't start any earlier than that.