In my case I do a big amount of grog with 3-4 tablespoons through the kneading ritual and then I add 1 or 2 if the first amount (2 big "shells") is not enough. I drink it as fast as possible first and the second round more slowly, to avoid stomach fuckery. The time between rounds is usually not so much, 20-30 minutes. More is a bit pointless in my case, and less is not enough.