This may save some time.  I have been asked this on numerous occasions.

1.  Why did you change from a domme to a submissive?     Long story short.  Was at a party with a mix of vanilla and lifestylers. A woman, older and very beautiful, seemed to track me down and wanted a conversation.  We talked through the evening and arranged for me to visit her at her vacation home for one or two nights under the pretense of me topping her.  We started playing and things got very heated and she ultimately flipped me. I was bound and used as her sex toy for the next three days.  That was 18 months ago and that experience has played on my mind since.

2.  How long or when was your first experience?   I had got to know a girl who was friends with my older sister.  She asked me to spend the weekend with her while her folks were out of town.  We were having a few beers and fooling around and she asked me if I would be game to tie her up.  She wanted to feel what it was like because she thought it might be sexy. She instructed me on how to tie her and once complete I watched her struggle against the ropes. I was getting more and more aroused.  I didn't understand it or why I liked it so much.  After a while I asked her if she want me to let her go.  She looked up at me and asked me if I wanted to kiss her.  It was all over after that.  She wanted to be bound and I wanted to touch her and kiss her while she was bound.  It was a weekend that changed my life.  I was 17 at the time.