I was 10.... My Mum hadn't had the talk yet as she thought I was too young. I was at home playing with my Sister and then the next minute it happened. My Mum sat me down and told me I was a young woman now then on I had permanent PMS lol.... nightmare teenager. Since I was 10 my periods have never been regular I go months without them.... there is no regularity with them unlike my Sister's which are like clock work.