It depends what office your application is at, I am at the Hamilton office and it took just under eight weeks until I got my oath date (which is for 2 weeks after that)
I checked in the tracker, it was updated today and says I'm scheduled for the 15th. I believe the official letters come in anywhere up until 2 days before ceremony. I'm at the Hamilton office
Did you have to do fingerprints last year? I did, and when they expired this year my background changed back to in progress and they requested I do them again
So I actually emailed them on a Friday, then a week later I had no reply still, so I emailed again the following Friday and on the Monday they replied to the second email lol! Yeah that's the email from my invitation
I passed test around Sept 10th, then they asked for more fingerprints, and then a month later they changed status to decision made, now its just the wait for oath
I got an email today telling me my application was approved mid Oct and I should get an email around 6 weeks from then with oath date in it so, fingers crossed!!