Congratulations! Montreal office will contact you through email and via your mycic account. In our case, both the sponsor and the PA got the landing appointment letter via email, and my wife also got it on her mycic account. Montreal office is known to be very busy (slow). In our case again, it took 8 weeks to get the invitation letter, and to weeks more for the actual landing. However I have seen on this forum people getting appointment in about 4-5 weeks after DM and some even landed in a secondary office (probably that CIC was trying to clear the backlog).
On site, everything goes fast. From the time your name is called, it will take less than 10 minutes to be done. You'll be asked very simple standard questions (have you committed crime, were you denied entry, any dependants that are not listed). They might ask the sponsor if he/she is still willing to sponsor the PA. Then give you your CoPR and ask you to check it and confirm that there is no mistake, then you sign it and they tell you: congratulations! You are now a permanent resident of Canada.
As soon as you want after, you can go to a service Canada office and get your permanent SIN (ou NAS en français).
Also, if not already done, you can register to RAMQ with your AIP letter and your CSQ.
And the final and most important step: you make a party to celebrate the end of that long journey!
