As far as I know, all the provincial nominee programs have some form where you state that you intend to settle in that province and you sign that.
A couple of years ago, immigration started going after people who get their PR through PNP's and do not land in their PNP province. They decided that if such persons are unable to prove that they are going to their PNP province, say having a transit ticket taking them there or giving the immigration officer some other good explanation why they aren't landing there, they can withhold their PR card until they show up at their PNP office for an interview. If the persons admit that they are not going to settle in their PNP province, they may decide not to give them their PR at all.
However, as far as I know, the PNP's are at least not yet going after people who have already landed in their PNP province and gotten their PR and then leave. I would still recommend going to your PNP province and trying to find work there. Give it 6 months and if you still can't find anything, you can go. That way, if they ever do decide to start going after people who landed in their PNP province but didn't stay there, you can at least say that you did intend to settle there and you tried but couldn't find a job. There is no official minimum time you have to stay but you must intend to settle at least when you land.