Hi..
Typically whats mentioned on the stamped visa is the actual date of validity for landing purposes which typically is one year from the date of medicals.. And they usually decide on the case with at least three months remaining for the medical to expire..
I am also aware of cases (where the time frame for landing is less than 3 months due to expiry of medicals), where CIC has gone back to the applicant asking if they can land in the period or would like to redo their medicals..
Its upto the applicant to take the call then as the stamping itself could take upto 4 weeks if not more leaving lesser time to land..
It depends on what stage your application is in and when your medicals expire.. sometimes (like in ours), the medicals was extended by CIC by themselves in Jan 2018 (they were due to expire in April 2018) till Jan 2019. We received our Golden email on 16th October 2018.. that means in all probabilities we may receive our passports with approx 60-75 days for landing.
We don't want to do a remedicals and delay the process further so we are going ahead with the landing even if given a choice..