Is the visa valid from the moment I enter Canada?

[redmapleleaf]

After studying here in Canada, I will apply for the post-grad work permit and wonder when the beginning-to-expiry time starts.

The post-graduation work permit is valid for 3 years.
Do the 3 years of post-grad work permit start from the moment I receive the approval/port of entry letter or from the moment I receive my actual visa at the border?

Thanks

 

[redmapleleaf]

By the way, I'm talking about the date of issue, the date from which on the 3 years of work permit are starting.

 

[Satvir Singh]

You work permit start when your application approved.