From what I went through, it was roughly 5 weeks after submitting my application that I got an invite to sit the AST (application submitted end of September 2014), then about two weeks after that I had my interview.... then things went slow! I had my medical end of January 2015, the doc there said my bh was high I needed a 24hr BP monitor.... blah blah for months! Then finally got the all clear from Crapita beginning of May. Did my PJFT a week or so after that, and now I have my PRTC in September with a potential start date of December 2015.
That's what it can take, i'm applying for flights ops btw!
It can be frustrating when you see people who have only applied a month or so ago and they're off to prtc already.... but he ho getting there!
Good luck btw