The Bank of Canada dropped the overnight rate by 0.25% today. Stay tuned to see what lenders will do - one lender has dropped their prime rate by 0.10%. The last BoC rate drop was in January 2015, and lenders dropped their prime rate by 0.15%, compared to the 0.25% BofC rate drop.
Your lender will usually send a notice in the mail advising of their actual prime rate change, if you hold a variable rate mortgage or line of credit.
Note - next Bank of Canda meeting is September 9, 2015.