In Ontario, some Public Health Units that are not using the provincial booking systems have opened up bookings already. I am in Ottawa... so for us we do have to wait until tomorrow morning. As for pharmacies, Wal-Mart and Costco have set up online waitlists. Some physicians have taken bookings, but my understanding is that very few of them have received confirmation of when doses would be sent to them.
There is a small initial supply of doses that came into Canada yesterday and the rest of the shipment is coming in later this week. Supply is not going to be the issue - the reason why it may take 3-4 weeks to complete is the ability to administer all of these doses