It's a simple question.
Non Canadian Instructors need to know that it will take 15 hours ground and 15 hours air time (or more) before they can do a class 4 Instructor ride. Getting a job right now is relatively easy and all Canadian employers need is a labour market assessment
And advertise the job for 3 months,
You can scroll thru Pilots / Instructors wanted and spot the telltale adverts written for this purpose.
That will give you a list of those employers.
Once with a Class 4 flight schools report months of delay by TC before granting class 3 upgrades after 3 first solos and 3 licence reccomends.
TC management also seek to indirectly and improperly deny Class 3 upgrades to instructors with foreign instructing experience and schools should triple check all such paperwork to minimize expected delays that should not be happening.
It's a lot easier for foreigners to get any other flying job than instructing but it can be done providing you very clearly understand the requirements which become simple enough once you have seen it done once.
The problem is getting it right the first time as you may not get a second kick at the can.