There is absolutely no way to know. It is possible to be exposed to HPV (high risk) with your very first sexual contact (it doesn't have to be vaginal intercourse).
I was exposed to high risk HPV at least 16 years ago, but it is possible it was as long ago as 26 years ago. :shrugs shoulders: There is no way to know. Since I was just tested back in December, it was some time in the last 26 years.