My bf ejaculated on outside of my vagina and i was on my period days ,my periods were just started on that day ,is there any chance of pregnancy?

No, unless...: Unless that day was not really the first day of her normal, regular menstrual period, there is "no chance" of pregnancy. In other words, a woman does not get pregnant from sperm she receives on the very first day of her normal, regular menstrual period. Of course, life can surprise you sometimes, which means all couples having sexual activities should be ready for an unexpected surprise baby.