If your PR card is still valid, you don't have to appeal yet. Wait until they realize that you don't meet the residency requirements and appeal then. This could be when you next enter Canada, if they note that you haven't met the residency requirements and start proceedings to cancel your PR status. They would then give you a month to make your appeal. This could also be if your PR card expires before you get to Canada and you need to apply for a PR travel document, you would have to appeal to them why they should let you back in.
If you were to get back into Canada with your PR card without anybody noting that you had not met the residency requirements, you could stay in Canada for 2 years without asking to renew your PR card and therefore meet the residency requirements again but if you applied to renew before you meet the residency requirements again, you would have to appeal to them why they should let you keep your PR.