I poured the dregs of a Boulevard Saison Brett into 5 gallons of a saison in a 5 gallon carboy. Now there's a white film forming on the top of the beer. Is this a le forming? Does Brett do this, or would it be some other sort of infection that's doing this? Either way, how long should I wait to tast it? It's only had the Brett for two weeks, so I was going to wait for a while longer anyway. Are there visual clues I should look for? This is my first experiment with "wild" yeast.

Sounds like you have a pellicle started. Congrats on your first sour beer. Now forget about it for 6-8 months

You just reminded me, still have to do something with my brown from October...
Have fun with the little beasties. Doing my 1st Sour mash on Sunday.

DO NOT DISTURB THE PELLICLE! Do not taste it until the pellicle drops. Like Eltharyon said, forget about it for 6-8 months. The pellicle prevents the Brett from oxygen while anaerobic fermentation occurs.

Thanks Hoser. I'll keep hands off until the pellicle drops.

Depending on your OG I would give the beer a taste after 4 mos and see if you like it. If you do, then by all means package it up providing the FG has finished below 1.010. Depending on your flavor threshold for brett phenolics then you might want to let it go either shorter or longer. I have had best results with aging my brett beers in a keg in cool temps between 50-60 degrees. Sometimes letting them sit too long at warmer temps really allows the brett to run away with your original intention of your beer and can make it overly goaty, horsey, sweaty, and farmyard like depending on the brett strain.

Just some food for thought....