I've used Brett in several beers. I've always added to the secondary or to the keg. I have one keg dedicated to Brett beers (my Flanders Red is in there now and is actually an all Brett beer. Wyeast Lambic Blend in the primary and Brettanomyces Lambicus in the keg). I plan to innoculate my 7.5 gallon Bourdeaux barrel soon. I love the more intense Brett character from the Lambicus strain. The more sour and acidic the better.