Amazing, soooooo may different epiphanies and timescales!
I still don't 100% what my realisations mean over the years, been a verry sloooooooow process of discovering some anomalies with my identity that other boys didn't have, then assuming there was an external influence to these inclinations, before looking inward and exploring the feelings that appear to be very much coming from within. Ultimately, its been one big exercise in personal fault-testing. And I now appear to be confronted by a whole panel of flashing warning lights and waling sirens informing me that my male identity appears to about to self-destruct after decades of being corroded away by a more powerful identity within that I still can't explain or understand.
Age 10 - became convinced I was a woman in a pastlife as I felt an affinity to femininity (possible musical band name, that) but could not explain why I felt I had been one.
Age 13 - Had a dream that I looked female and felt feminine. Woke up feeling a strange sense of energised melancholy and wistfulness. This has continued.
Age 14 - Started crossdressing in private. Became interested in dating girls like a hetero teenage boy, but simultaneously needed to dress up & feel pretty to get turned on.
Age 20 - Became self-aware and realised that how I wanted to dress was feminine and that I always imagined I was female singers or actresses in my daydreams.
Age 23 - After a major purge of clothes and feminine attitudes, a massive urge to dress-up came back with such a force, that I had to explore it to find out why.
Age 25 - Tried visiting mediums to find out if I had a female pastlife or were being haunted by female spirits. No answers from those avenues.
Age 25 - began dressing up and exploring my inclinations, and since then, there's been a conscious and un-conscious slide towards a female identity, for better or worse.
Age 27 - Beginning of current journey.
Lots of other milestones and realisations, since 27 though its been an amazing, refreshing, enlightening journey, yet also a massive pain in the ass & a scary experience.