You could divide the off season in 1/3's. The first third starts once everything is put to bed and after the first substantial snow fall that is too much to reasonably remove, somewhere around 6-8". During that time you're on pins and needles praying for more snow and no rain. The middle third is now: full on winter. If there is any warmth during the day it very short lived. Hopefully, there is enough cover to withstand the dreaded mid-winter season "warm spell/rain event". The weather is generally cold and I am mostly inside. It's only me and, as anti-social as it sounds, I like it because there is very few distractions. The final third begins somewhere around mid-February. With the days getting longer and with some heat in the sun its not unusual to see some turf areas begin to open up. Also, if you have ice problems now is the time when you start to addressing them. Any earlier doesn't necessarily make sense based mostly on the short days, lack of warmth, and the potential for severe winter weather.
Along with the first 1/3 the final 1/3 is where, I feel, some of the greatest potential for turf damage can occur. Mostly this suspicion relates to damage caused by the development of ice (leading to anoxia: low oxygen) and its removal (possibly causing crown hydration: water taken up by the turf freezes and burst cells when temperature drops). But even without ice an early melt that saturates the surface followed by a severe temperature drop or sustain cold snap can also lead to damage (again, crown hydration). The one good thing about the final 1/3 of the season is you can usually address problems and somewhat lessen their severity since the weather in usually changing for the better.
Sometimes you get a season like we've had so far. The first 1/3 was not the best but we've had way worse. I suspect the biggest impact may be increased disease on those fairways that were sprayed early on for snow mould and saw a very large amount of rain on a treatment that doesn't like rain. Right now we are in the middle 1/3 and I feel sort of guilty since it has been an easy time with no obvious problems. We did get some ice as mentioned in a earlier post but as of yesterday it is still pretty loose and things look and smell "green". If the rest of the off season remains similar we could be coming through looking pretty good. Oops, I jinxed it, didn't I?