I would have posted this a lot earlier but I had a commitment to deal with. So, here's the results of my "dead cold" start:
8:00am, 31 degrees. The engine fired up just as soon as it always had, but the idle was a little lumpy, struggling, which disappeared the instant I applied a tiny bit of throttle. So then I hold the throttle open just a crack - just open enough to keep the idle steady. I did that for 30 seconds or so, then I let it idle without my help. Perfect. Smooth, low, and really quiet. Just needs the smallest warming-up period. I can deal with that.