My first crossdressing experience was when I was 6, although I always had the urge to wear female clothes before then. This happened during a Xmas panto performance/rehersals in my infant school, where my friend and I took on the roles of "Kings of Topsy-Turvey Land" in Sleeping Beauty. We were "topsy-turvey" because the top half of our clothes were masculine, but we both wore a mini-skirt and pantyhose below! Looking back, I should have been embarassed about that cruel joke put upon by our teacher, but I wasn't. In fact, I was SO pleased that I was given the opportunity.
It was when I reached the age of 11 that I finally had the courage to fully cross-dress, and have continued to do so for 22 years and counting.