for me anyways, when they tell you things will take 6-8 weeks or even 8 months or any kind of estimation of time...they're usually accurate. After AIP, it took exactly 8 months for my DM and visitor's visas took exactly the time it said on the website.
I've seen people go from 2 months after AIP to getting DM, but I really dont know what you gotta do to get that haha.
I also think Ottawa is known for being pretty slow in terms of booking interviews. It seems what they do is they wait for a certain amount of immigrants and just book them for 1 date. Hence the 6-8 weeks. I'm sure other offices do that too, but not a whole lot.