When brett has to struggle it creates more funk flavors. When situations are ideal it creates more clean flavors. If you add brett to a "finished" beer that has dextrines to slowly chew on it will create more funk flavors than when you pitch it in fresh wort. So you can have a 100% brett fermented beer that tastes cleaner than, say, Orval where the brett is added post fermentation.
Actually, I think a lot of wild beer brewers are moving away from this line of thinking. The reason Brett makes a funkier beer in secondary is because a Saccharomyces primary ferment creates the precursor compounds that Brett turns into more complex flavors. So in Orval's case, for example, Brett has plenty of esters and phenols to work with from the primary ferment with a Belgian ale yeast.
I would recommend a starter for the Brett. It may take a couple of steps to reach target pitching rates, given the lower cell counts in commercial packaging. Brett starters also take longer than Saccharomyces to get going. Each step may take 3-5 days (maybe even a week for the initial step).
The point of the starter isn't so much to ensure a clean beer, but to get to full attenuation in a reasonable amount of time.