I try to go by the basic recipe, which is 1 TBS grains to 1 cup of water and 1 TBS sugar.
I think, the more SKG [kefir grains] you have in a recipe, the faster it will ferment, so to keep the alcohol level down, taste test it often and strain it as soon as you think it's ready.
It's going to take your grains 3-7 days or so to really get going. The first batch may not be too great, but they will improve fast.