Pizotifen, How well does it do?

I have been prescribed Pizotifen by my GP, She said to come back in a month, but from such a wide community of migraine sufferers, but my attacks took a turn for the worst, every day.

I'm only 15, popping pills like smarties, so how long roughly would it take before it should take a full effect?

Bearing in mind everybody's different medically, I take 1 a day, but can take two if doesn't work.

Thanks

Tom Hughes