Using NYC as a reference point, there will be a couple hours of light snow, followed by a couple hours of moderate snow. Then there will be a big thump between 12 and about 6(ish)pm before any mxing. I think 8-12" is a good forecast. I wouldn't be surprised if there was a little more if it snows at 2-3" an hour for a couple hours. With that said, it also wouldn't completely shock me if it mixed earlier. Usually I would think the NAM would be spot on with the mid-levels. I think it's too aggressive in this case.
I kind of like the idea of a thump then nyc turns to sleet for a couple hours then precip shuts off completely or there's some freezing drizzle.