If you have been pre-approved for a mortgage at a specified rate, but as of April 19 have still not signed the purchase agreement, be forewarned that new qualifying rate rules will apply.
According to the Canada Mortgage and Housing Corporation (CMHC), a mortgage pre-approval does not represent a binding agreement for the lender to provide the said funds. Therefore, unless you sign your purchase agreement prior to the April 19 cutoff date, the rate you qualify for will be subject to the new rules.