It acts NOW. As in, as soon as it hits the tummy. daughter says maybe 2-3 minutes to start to have effect. But its a "hard candy", so you have to suck on it, not just swallow. Does come in different strengths - start with the milder one, the stronger ones take some getting used to.
Sorry, no cookies-and-creme flavor - it comes in "one flavour suits all" - as in, Ginger flavor!
Ginger also has positive effects on headaches in general, including migraines. We keep this stuff in the house all the time now.