Freelancer - providing Service to Canadian Market (Toronto)

Hello people,

I hope someone can share some experience/knowledge about being a foreign freelancer / entrepreneur providing service in Canada.

Background:
I have a sole trader company registered in Austria and doing technical short/long term project work for various companies as freelancer.

Due to personal reasons I will move to Toronto in March.2014
I read a lot of rules and regulations for foreign companies providing services in Canada.

As of now I come to the conclusion, that acc. to GATS - General Agreement on Trade in Services, you can acquire contracts with a max. period of 3 month once a year. You just need to show the contract in order to get a wok permit. (No LMO Needed)
My problem is that, 3 month is quite a short time and wonder if someone else hast experience with such a situation.

Is here anyone how is a foreign freelancer providing services to Canadian companies????

What are your experience???

Thank you so much in advance for your help.

BR,
Martin