What temperature are you planning on using? They recently posted this on their Facebook about their Melange Blend and Farmhouse Sour that might help you on the fermentation end:
"We've been been conducting some experiments with our Mélange Sour Blend and Farmhouse Sour Ale in which we fermented a pale wort of ~5 IBU at 70 F for 3 days, followed by 78 F for 2 weeks. While the beers were still young and the Mélange needs time for the Brettanomyces to work, there was marked acidity in each.
For a fast turn around sour with either blend, you should get good results at 70 F for 3-4 days to allow the yeast to complete a bulk of the fermentation, followed by 76-78 F for 2-4 weeks to ramp up the lactic acid bacteria. If you want the beer to acidify more slowly, we recommend keeping the temperature at 68-70 F. Slower acidification is particularly recommended for the Mélange blend in order to ensure the pH doesn't drop too fast and inhibit the Brettanomyces yeast that will continue to develop the flavor profile of the beer over a long period of time. If you mature the beer on the cooler end, the temperature can always be raised later (and perhaps some extra fermentables added) to increase acidity after the yeast driven flavors fully develop.
Cheers!"