I stir for lees contact if at all. Then only weekly or so. Otherwise, let it do its magic. Do give it a sniff test every week or so to make sure nothing is going wrong.
MLB is a slow and silent worker. As long as conditions are right, temp, mlb nutrient, SO2, pH, I have never had one not complete and has taken weeks or sometimes months.
Some folks are able to tell by taste, but I prefer to run tests. You can either use paper chromotography, which simply tells you whether or not you still have malic in your wine, or use testing strips which give an indication of the quantity of malic in the wine.
Craig, what type of testing do you do? I have 6 carboys in MLF for 4 weeks now. Wasn't planning on any tests BUT starting to over think this. Thanks, Roy
I do the malic test strips. They are easy to use. I don't get excited about color differences, until it is nearing done. After it reads done I always let it sit another month, just in case I misread the strip. I don't open the carboy during this time. I think many people get overly worried about the no sulfites while waiting and give up.