There's 2 options, depending on where in Ontario you live. The most common option is to find a gender therapist in your area, talk with them about your gender issues and if you together come to the conclusion that you should be on hormones, you will get a recommendation letter that you then take to an endocrinologist who will prescribe the hormones for you. It might be a good idea to look up the endocrinologist first just in case it is like Alberta where there is really only one transgender endo and he requires that you talk to a specific psychiatrist, not just anyone.
Option 2, if there is an informed consent clinic near you, or within reasonable driving distance, and you are sure that you want to be on hormones and are willing to take responsibility for their effects yourself, you can go there and expedite the whole process and they will assess you and have their own endocrinologist to prescribe the hormones for you.
There are a few people on Susan's that are from Ontario, so they can probably help a little better as it can be different in each province. Hopefully one will drop in here.