You can graduate in one of the three terms:

1. Fall: thesis turn-in deadline is Dec, and your graduation date is Jan;
2. Spring: thesis turn-in deadline is May, and your graduation date is June;
3. Summer: thesis turn-in deadline is August, and your graduation date is Sept.

Typically the semeser before your deadline, you would declare intent to graduate with the department and with MIT. Currently Heather sends out an email every semester when it's about time to ask students to get on degree list if they intend to graduate soon.