Different... Yes.
Like others, I now see that some signs of being different were present at an early age, and became more evident as my contact with other children increased. However, at the time I myself didn't realize it. Since I was categorized as a boy by others I also did. There just were many things I couldn't understand.
In grade school, throwing snowballs at the tip of a fl->-bleeped-<-ole, I couldn't understand why boys jeered at me for throwing underhand. I also couldn't understand why they would throw a fit if I put my arms around them. Later, when they started shunning girls I once agin couldn't understand why.
I also just couldn't understand why boys in books wanted to grow up fast and become men. I certainly didn't want to.
However, at the time I didn't think this "not understanding why" made me in any way different. I just was baffled.
I guess others did see some difference, though, since—depending on the school—most boys either simply avoided me or called me homosexual. It seems strange now, but at the time I was only aware of being an outcast without understanding why. To me I was just myself.
I'd say I really admitted/embraced being different around tenth grade. It was around then that I gave up attempting to be liked, shaved my head and then let it grow long, and finally left the school because I wasn't allowed to select home economics for the next year even though it and industrial arts were the only "elective" courses we were offered.
That said, I did even in grade school have an inkling. I fell in love with the Tip/Ozma story the moment I discovered it. I read it over and over wishing I'd discover myself to be under the same spell. I ached for and willed it to be true, and for the spell to be lifted. Since I was also pragmatic another part of me denied the possibility.
I guess I at least already knew that I wanted to be different than what I was expected to be.