Hello,
while I live in Ontario as well, changing my gender marker without surgery only applies to those born in Ontario. As I was born in another province, I had to wait till I had my surgery and then changed my birth certificate.,
To get my documents signature guaranteed, I just Googled "notary public", and found one close by who charged $40.
Going through CAMH and Montreal?
Good luck with the process, hope you get a better answer than what I was able to provide.