ANDY'S ANSWER: Those can be symptoms of your period, or the flu :-)
Usually a first period will come about 2+ years after your breasts start to develop.
Some girls notice a thick mucus discharge from their vagina about 6 months before they start their first period.
Even after you get it, it will likely not be regular for at least another year or two.
Your body will decide when it ready to start menstruation. Just be prepared by always carrying a pad in your purse because you'll probably be caught by surprise one day and there it will be.