So are you looking for a straight Lacto soured beer then? From what I see on TMF blog, the Bruin blend just had Lacto and Sacc, which you probably already know by the sound of it. Anything with Pedio or Brett, which are both in most sour blends, likely wouldn't be where you want them after such a short time frame. You might have faster results just pitching some Lacto with an ale strain.
I'm of the mindset that unless you are intentionally quick souring something via sour mash or kettle souring, expect to wait at least a year (preferably longer) for good results in most sour styles, aside from stuff strictly Lacto+Sacc low IBU stuff like Berliner/Gose/Etc. A dark, complex beer like a Bruin doesn't seem like something worth rushing. Plus the IBU level is usually a bit higher (20s), which is way too high for most/all strains of Lacto to do much.
I haven't seen much when it comes to doing quick sours with darker beers (Most being Saison, Berliner, and Gose), but I am sure the info is out there.