I used 3278 in one of my lambics and didn't make a starter for it. It did its thing for 2.5 years and I didn't pitch fresh yeast at bottling; there was still enough horsepower left in the yeast to bottle condition (left in the bottle for a year before sampling). I would be very hesitant to stir it at all. I made a kriek and racked off the cherries about a week or so before bottling, to get the fullest effect from the fruit/pits. In your case, I would let it sit until sometime next spring, maybe even early summer. Then package/bottle and let sit until the same time the following year. It takes a while to make a good lambic, but you will be rewarded when you taste it.