Just drink 1 ltr per day, although I drink 1 ltr for 7 days before, many of us only do it for 3. The apple juice contains malic acid which softens the stones making it easier for expulsion.
By the way, I'm also doing a flush this week-end - e/salts and O/O mixture Fri night and flush on Saturday Morning. Come to the Liver Cleanse Support Forum and we'll swop stories.