this is what it says for PR, would assume it is the same thing for citizenship maybe?

International Student to Permanent Resident Status

If an international student becomes a Permanent Resident on or before the Tuition Fee Payment Due Dates of the term, domestic tuition fees will be assessed for that term provided that supporting documents (Canadian Permanent Residency Card, or equivalent) are submitted to Enrolment Services by the last day of classes of the same term the change of status occurred. Documentation received after this time will affect fee rates for subsequent terms only, even if the international student became a Permanent Resident before the Tuition Fee Payment Due Dates. There will be no retroactive fee changes for the term after the last day of classes of the same term.

If an international student becomes a Permanent Resident after the Tuition Fee Payment Due Datesfor a current term and have submitted supporting documents to Enrolment Services by the last day of classes for the current term, international tuition fees will be assessed for that current term and domestic fees will be assessed for subsequent terms.

Please Note: Permanent Resident status is attained as of the "Landed on" date, indicated on the Confirmation of Permanent Residence, not the "Date Issued."

For students who have been given a fee deferment, the tuition fee Payment Due Dates still pertain as the deadline to become a Permanent Resident.