You asked almost this same question right here...so I'll refer you to the answer to it. Please remember the guidlines and don't double post the same question.
Additionally, there are many many things that can affect your period (eating habits, stress, over exercising, etc.), and within the first 5 years, your period probably won't be super regular anyway...however, masturbation and sex do no affect periods.
I highly suggest you do some reading up on how your body works.
There's hair there for a reason!
"Never insult an alligator until after you've crossed the river." ~Oriental Proverb