Does your cherry pop when you start your period?

No, your cherry does not pop when you start your period.

The term 'pop your cherry' refers to when the hymen is torn - the hymen is skin surrounding the vaginal opening, it has nothing to do with menstruation and it can usually only be torn as a result of vaginal penetration. The hymen can be torn when you first have sex, but not usually as the hymen often allows for penetration and only tears if penetration is rough. Menstruation has absolutely nothing at all to do with your hymen, it will not effect your hymen at all.