it totally depends on the brand, and concentration. can you email whoever you bought it from? did you mix it yourself? or is it homeopathic? if so, those are usually taken anywhere from 3x to 6x/day.
magnesium and potassium help with muscle soreness and can help prevent spasms. i take 180 mg of each twice a day, but i've had a lot of trouble with spasms- you may not need to take that much.