Perfect! I was hoping you meant principal applicant and not pr!
It's hard to know the timing, since everyone is different. But expecting after Songkran 2018 sounds like a reasonable thing since their goal is 12 months or less. I hope you will not be disappointed. As long as they don't require an interview (which can add a significant time) than 12 months is reasonable. Some have said that if it is a "simple, straight forward case" with no red flags, no interview and no medical complications, than it has been about 7 to 9 months on average in the past.
Our timing applying from Thailand, to give you an idea. We applied beginning of January 2017 (including our police check). We got SA and file transfer February 2nd. We were apparently sent AOR2 February 20th. We then didn't hear anything until our medical was requested July 25th. We then did our medical beginning of August and just found out that we have to do further tests (spots of lungs, so sputum test and a second X-ray 2 or 3 months later). Another thai citizen has almost the exact same timeline as us, except instead of further medical tests, she got a PPR this week!
So, if you don't have an interview, then you could maybe get your medical request, police check request and background check in progress around October/November, and if no inactive TB or medical complications, maybe PPR in November/December. But that is all hypthetical based on only TWO January 2017 thai applications... Also, you normally have 12 months to move to Canada from the date of your medical, so even if you got the PPR in late 2017, you could still choose to move after Songkran if you wanted...
About the police check... I sent in our police check with the application so I'm not sure when it will be requested. I would probably go ahead now and order the police check in Bangkok so you have it ready as soon as they request it to reduce delays since it normally takes a month or two to get it. We were able to get it without ever having the official IRCC request for police check (since we did it ahead of time). If you need help on how to get it quicker or from out of province, you can PM me.