When you think about living on campus you should know that you will not
have your house until 15th August, so, if your programm starts before you sould get a place to live before having your house on campus, so you can have a sublet from another family or single (depending on your situation) . Usually families go back their countries on summer and they rent their appartment on campus housing.
Where can you find a sublet?
https://housing.mit.edu/graduatefamily/sublicense_center
https://housing.mit.edu/off_campus/mit_off_campus_listings/
Also there are two email adresses where you should send an email asking if somebody has the apartment available for subletting for the period you need. In this case all the neighbours of the on campus building will receive it.
westgate-forum@mit.edu
eastgate@mit.edu
Other places to look for a sublet or to rent a house for 1 or 2 months:
my Boston experience 