Last year I made my first sour beers, and did a typical starter with my brett. They didnt seem to do much. After studying Chad Yackobsen's Brett Thesis, I saw that he found brett needs more time. He states that it goes through growth phases, grows, stops, grows, stops, grows again. Seven days is what I got out of it.
So I pitched Wyeast bret lambicus on the evening of July 9. Peeked in on it every day. After 24 hrs it had a slight powdery cloud at the bottom. After 48 hrs, no change. After 72 hrs the powdery cloud seemed a bit thicker. Here it is at day 4.
I'm going to let it go the full 7 days. I'm curious to see if that third growth phase is a dramatic as the second one.