Suggest Drugs For Preponing Periods

Hi Doctor, m a 21 year girl...i want to prepone my periods...As we r going for a tour to northern india and would be visiting temples starting from 16rd sep till 22 sep. I usually get my periods every after 28 days and my last period date was on 18th aug which lasted for 5days....i want to prepone my periods for about 3 days before i.e. from 10th onwards i should have my periods...please consult me a safer medicine which wudnt cause me any side effects too....i wud be very thankful to u :