I do one week for the first fermentation and 2 days for the 2nd (bottle) fermentation. It just depends on how sweet you like your Kombucha, there isn't really a "right" time to stop it. There are many factors besides personal taste that will affect brew time: what kind of sugar you use (the less molasses the easier for the yeast to digest), how warm it is where you store it during the brew, the health of the SCOBY, etc. I would taste it after a few days and see if you want to add more brew time.