as different people respond in variable ways there is no fixed timeline to give other than that usually removing an offending substance shows pretty quickly. Remember kefir is in a different category that general "dairy".......
If it is seasonal allergies triggering the eye tics (which is a commonly reported issue) than you may want to try to use an anti-histamine and see if that helps. I prefer natural ones so as to reduce the chemical exposure from the conventional rx and otc products
here are some good alternative natural anti-histamines http://www.webmd.com/vitamins-and-supplements/lifestyle-guide-11/allergies-allergy