I was in 6th grade so 11 or 12 when I had my first orgasm. I'm sure I explored, rubbed, played before then but I didn't get the big "O" from it until then.
I recall at the age of 7 was the first time I ever felt sensation in my breasts. I was lifting myself up on the sink to reach my toothbrush and as I slid down to get my feet back on the ground, my breasts slid against the porcelean sink and that feeling raced comletely down my center straight to my groin. I thought "wow, what was that? It felt so good!" Followed by several slides up and down the sink!