Is it possible to ovulate years or months prior to your first menstruation (menarche)?

NO but 2 weeks prior: Your first menstruation occurs about 2 weeks after first ovulation. Anytime a woman ovulates she will have a menstrual period about 2 weeks later unless she becomes pregnant.

Yrs or months/no: Early cycles in pubescent girls can occur without ovulation when chronic estrogen buildup self destructs. After several months and by the end of the first year, 95% of cycles will be paired with ovulation. A girl might ovulate with her first cycle, presenting the possibility of pregnancy in a kid who has never had menses. I saw this happen during my training.