My first winters I kept a detailed log of what to wear at what temperatures. I helped that I was mostly commuting the same distance and tine every day, so comparing was easy. So I'd get home and note down - "wore x, y and z, temp was tt, some wind. I was a bit cold there, but a bit too hot there, Should have worn xx and yy instead". And gradually I figured out where the different temp cut-offs were for the clothing and rides I have.
Keeping comfortably warm but not overheated is so individual, depending not only on the terrain and the weather and the wind, but also on how hard you ride, how much does your pace change, do you charge up hills getting all sweaty or just amble up at a gentle pace, do you go all out on the downhills getting freezing etc etc. Sometimes you just have to adjust your pace to what you're wearing, not to how you want to ride...
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett