Juniper Berries to Delay Menstrual Cycle?

My sister and I are going to Hawaii this summer and, unfortunately, my mentrual cycle begins the very day we are leaving and we cannot reschedule the trip. I have read that if I drink three cups of Juniper berry tea three times a day I can make my mense come earlier. Is this true?
This issue is very important to me as I will be snorkeling and doing other in-water activities and I don't want to single-handedly attract the whole population of Great White Sharks in all the islands of Hawaii. If this would work, please let me know.

Herbalists work to restore a natural balance that will allow the body's natural energies to promote healing. We can suggest diet, herbs and lifestyle factors that will help to regulate the menstrual cycle, but not to delay it.
Juniper berries contain a strong oil. They should not be consumed for more than 2 weeks without a break.