I voted for 10+ because I didn't know I was bipolar until I was diagnosed at 53. Looking back, I probably had numerous episodes, especially of depression, and didn't really experience mania till around age 35. But I had rapid-cycling BP for quite a while, both mania and depression, and the reason I'm no longer rapid-cycling is I'm finally on the right combination of meds in the right amounts. I must've had easily 2 dozen episodes in the time between the time I was diagnosed and the time I really became stable a couple of years ago.