The bill was signed in June 2017. Following that, the government tabled this implementing bill, Bill C-82, to enact the MLI into Canadian domestic legislation. Following royal assent to this bill, Canada would be in a position to notify the depositary of this convention that it has completed all necessary procedures to implement the bill in domestic law. Then the multilateral instrument would be in force, in respect of Canada, a three-month period after such notification.
On February 5th, 2019. See this statement in context.