OK i am reading some replies about staying in provinces after getting PR, there is a lot of grey area for this, YES the law or CIC rules don't stop you from changing the province but i have heard that when you apply for Citizenship then they do raise red flags at that time, in the citizenship app one has to put the past addresses and when these guys see that you moved very quickly from the province which gave you the Nomination then it raises questions which could further delay the process of citizenship, YES you still get your citizenship but not that easily or quickly. When a new immigrant lands in Canada, right on arrival he applies for a PR card at airport (the port of entry), the PR card carries the code for the category under which the immigrant got PR, so it is always going to stay on your record that you came under provincial nominee..............
another thing i have seen personally is that few of my friends who got PR through SINP, when they landed in Saskatchewan as immigrant they were called by SINP office in regina (after about 3 months) to come and meet one of the officers personally with proof about their residence/job in sask, those new immigrants didn't even apply for any sponsorship or anything, they just got picked randomly, for sure SINP office did that to check if they are still in Sasaktchewan or they bailed out and i am sure if somebody is caught changing the province (within 1 year time frame) behind the scenes there must be something which could hit the immigrant later on, may be during citizenship app, and that's for sure that the applicant will be banned for filling any sponsorship from that particular province.
Based on my experience i strongly suggest to stay in the province for at-least 1 or one and half year and if you don't get a good job in the province then you can leave anytime, but make sure you keep enough evidences to prove that you applied for many jobs but you didn't get any !
WISHING ALL OF YOU GOOD LUCK !