Well, the yeast clean up after themselves after fermentation is over. I know edwort kegs after 10 days, but that is for relatively low gravity beers (about 5.3%) and he cold-crashes them to let the yeast and anything else floating around sink to the bottom of the carboy before kegging. I waited 4 weeks for my first batch; 2 in primary, 2 in secondary. I'd say 3 weeks is a must. But then again, I've had plenty of patients when I made wine in the past, letting it sit as long as a year before bottling, so 3-4 weeks was super easy for me.