There are no rules for PNP on how long you must stay after your landing.
You must have had the intent to settle in MB when you applied as well as when you landed. This is what you sign when you apply under PNP, that your intent is to settle in the province.
It is possible that you could at some point be accused of misrepresentation if it is clear to immigration that you did not have this intent. A sign of that could for example be if you leave your province very soon after landing.
As far as I know, they are currently not going after people who leave their PNP province soon after landing but in case they do in the future, you do not want it to look like you already had the intent to leave when you landed so you should preferably stay for at least a few months after your landing.
Immigration officers have been known to tell landing PNP applicants that they must stay in their PNP province for 2 or 3 years after landing, until getting citizenship or even forever but there is no legal base for such claims.
The charter of rights and freedoms gives a PR the right to live and work in any province.