I have answered this alresdy. You file 1040NR as you have not yet fulfilled US resident requirement (SPT). Since you have no Cdn residential ties since september, that is your departure date.
It is OK to be have no tax residence for those few months.
Part-year 1040 vs full-year 1040NR
Moderator: Mark T Serbinski CA CPA
Re: Part-year 1040 vs full-year 1040NR
After 20 years, I am severely cutting back on responses. Do not ask specifically for my help. There are a few others on this board that can answer most questions. All the best