There is a pretty good quarantine article in the article section. I think it recommends about 3-4 weeks, assuming you don't have to treat for anything. I guess it also depends on how careful you want to be too.
Yeah, I think the article recommends 30 days, but if you have to treat for something, you start the count back at 0. I just QT'ed for the first time, it was soooo frustrating waiting that long , but hopefully it was worth it