How To Prepone Or Postpone Periods?

I'm 15 and I'm going on a beach vacation for a week. My periods are just starting to become more regular but they don't have a definite pattern yet. I got it on the 2nd of November, then the 7th of December so logically ill get it again on the 12th of January which is smack bang in the middle of my vacation. Is there a way to make my period come earlier or postpone it. I know birth control is an option but im scared of side effects and i dont really want to mess up my body so young. is there a way i can make it come earlier?