The way it's written in the amendments, the minimum wage will be set at $15 per hour, and then on April 1 the year after these provisions come into force, the minimum wage will be adjusted. It will be based on the increase in Statistics Canada's consumer price index for that year. Whatever percentage that increase was for the previous year, that will be the rate at which the minimum wage is adjusted upwards.
On May 17th, 2021. See this statement in context.