I'm not sure of the date yet, it seems to be moving around as provinces are trying to come up with adequate regulations and sales but yes the rumor is true that all cannabis will be legal for recreational use this summer ( My city has the largest legal grow house in the world...hehe)
I didn't look into B-C's blockchain usage to track sales but definitely will have to look into it now and it would be a great way. The government of Canada is also working to have all of it's future public records recorded on blockchain and are currently working with etherium platform to do so.