You can choose to rent rooms/suites out for 4, 8, 12, or 16 months. All terms start either on September 1st, January 1st, or May 1st, following the school calendar.
However, you can do midterm bookings, which enables you to rent on the 1st of any of the other 9 months: February, March, April, June, July, August, October, November, and December. It is important to note that all rentals, regardless of their start time, will end on Dec 31, April 30, or August 31 - the dates on which school terms end.
HINT: To get the most results while searching, try choosing a typical school start date like September 1st, January 1st, or May 1st. Mid-semester bookings are subject to availability by the landlord, and you may only have a few options compared with listings for terms starting in September, January and May.