About 4 I would say.  Sitting on a bed with a friend brushing my hair and I knew I was just like her.  Not far enough in life to know that I was not, but can remember loving the feeling of content comfort.  It is one of my earliest memories.

By third grade, I was sure I was in the wrong body as I understood my birth sex and who I felt I am inside.

I would say most of my early memories are of being a girl. I remember vidly one occasion going to a bid department store with my mother and plotting how to reach the makeup testers on the shelves... of course I got in trouble but somehow was worth it. I think I was around 2!