I'm sorry but that is not how it works and you can see why this causes so much confusion for Canadians. It's not like a work visa, or student visa. With even a K-1 Visa which is a non immigrant visa they consider you no longer a resident on the day you cross and get that visa endorsed.
When you cross the border to endorse the visa you are no longer a resident of Canada, because that is the date you tell the US you are now a US PR.
When you file your exit taxes you will mark the day the visa is endorsed. If you get baby bonus, whatever the GST is call now they all go by the date the visa is stamped. If you get any of those they will want their money back for that month and they will be the first to figure it out.
The 212 days outside the US is for students and snowbirds, not someone who shows up at the border with a visa declaring that on this day you are a US PR. That is how they decide you are no longer a Canadian Resident.
Over the years we have had many Canadians end up with a bill. I'm not making this up, it's experience and time on here that has proven otherwise.