My Dad got some black "yuck" stuff on day 2. We are doing P&Bs (see I'm getting the groove of these acronyms) 4 times a day. I haven't gotten any that are black or dark brown, but I did get some sinking light brown stuff that may qualify (hopefully). That was day 4 for me.
We are on day 6 right now. Probably going for 8 days. Starting back on food slowly (although a big piece of chocolate cake sounds good). We will do a Liver Flush on Friday night and see how that goes.