Cooking/prep time does not include cooling or setting time. Don't use non-fat or flavored yogurt as the starter. I use Dannon plain and it works great. Natural Grocers or Whole Foods sells single serving, plain, not non-fat, which works well. Save some to use as your starter next time.
I've made this many many times now and love it. Easy, nutritious and has no ingredients that I can't spell. You can flavor it by adding a spoonful of jam, apple butter, or honey. Granola and fresh fruit is the best topper! The gelatin is useful if you like your yogurt more firm. I haven't used the gelatin because I always make it Greek, but am told that this is needed for some folks who just can't get theirs to set up.