I started a thread like this years ago and loved the response so I thought I would start it up again since it's been a long time and the population here has dramatically changed.
How old were you when you started and who's clothes?
When I was very very young, I shared a room with my oldest sister and for some unknown reason, I would pull her pantyhose over my pajamas at night when I was in bed. I woke up one time with her yelling at me to take them off and I stopped. However, I don't really count that...
When I was about 10 or 11 years old, my sister was going through some of her old stuff and found an old dress that she no longer wore. She dared me to put it on and for some reason I agreed. I took off everything but my underwear and put it on and pranced around the house in it. She had to tell me to take it off.
Months later when I was home alone, I remembered how fun it was to put on my sisters dress and since I was home alone, I decided to just look at some of the pretty dresses that my sisters had. Naturally, I didn't just look, I tried them on. I then added a bra. Then pantyhose, a huge turning point, and then heels. Since I have three older sisters, my teenage years were chock full of some of the best dressing years of my life. From time to time, I would fake sick and have the house and three full closets all to myself all day. Good times.