Anywhere from a month to three months (I'm not sure about treating tremors). If its not an extended release
capsule, you may also find that you need to divide the dose, and take it 4 times per day.
I use and extended release capsule, and even then, my doctor recommended taking it twice per day. When I was using the regular capsules, there was a very noticeable effect at the end of each dose. Just someting to consider and discuss with your Doctor.
Hope this helps.