Herbs to Delay Menstrual Cycle?

I was wondering if there was a herb to maybe make my menstrual cycle come late or anything that would effect it? I know this sounds weird but I have a very important event coming up and I don't want it then!

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.