I'm not sure if mine was a slow or a fast transition. When I decided to officialy start my transition I began with hormones. That was in April. At that year's new year dinner I came out to my whole family and started living full time as a woman. That would be 9 months, but I started doing things long before hormons. I gre longer hair, I shaved, plucked my eyebrows, started wearing earrings...
If you ask me which one is better, I say a fast one. I wish I had listened to my mind earlier when I was in primary school and I regret loosing all these years, I don't want to lose more.
But going for a fast transition doesn't mean pushing yourself to doing things you don't like or feel you're not ready to do. If you feel you want and can do something, do it, don't wait. If you're not sure, wait until you are, or try something similar as a test.