This varies based on each person's case. If you take my case for example, I am a single Applicant from Toronto (Scarborough) area.
1. My application was official received by CIC on 2nd Feb 2015.
2. I got my AoR on March 11th 2015 which was a full 37 days then things slowed down quiet a lot.
3. My File finally went to 'In Process' on 11th June 2015 which is a full 92 days since AoR.
So in overall if you take my case only it took a full 3 months, currently for Feb and Mar batches there are people who are past the 3 month period and there is still no update so it is hard to make an average time guess, you can always go through the excel spreadsheet for months between Jan till Apr 2015 and look for people in your Province to get an idea how long it took for them as your best bet.