Say, for example, that i get PR on 1st January. Do i then have to land within a certain time? I'm trying to organise everything and if i know i have to land in Canada within 1 month or other time frame, it'll mean i can sort my timeline!
You must activate your COPR document prior to the expiry date on the document. As soon as you do, you are free to [literally] turn around and leave Canada...and remain outside of Canada for up to 730 days without violating your Residency Obligation.
Many people do this and it's considered by most to be a `soft' landing. It's very common to enter and then return `home' to finish getting things in order.
The expiry date on the COPR is one year after the date of the medical exam.