It's my understanding that you need to step up the white labs brett twice. That's what I did with claussenii, letting the starter go a week each time. I also think you want to aerate the starter, no idea if stir plate or continous O2 is better. I just swirl mine periodically, maybe you can get enough growth in one step with more advance aeration. By the time I pitched, the starter had a pellicle and an odd smell, but the final beer came out very well, IMO.
Here's on from the recipe database - The Muse - All Brett L Blonde