When I've been on CN, I always just pick a time on Saturday to start. Then do whatever I want after that time. So sometimes the CN is 2 hours, sometimes its 10-12. I haven't noticed any difference.
I almost always have a Carb Nite less than 6 hours. Sometimes as little as 3. I wouldn't say results are much different as much as it's just a personal preference/trial and error type of thing.
^Same for me. The carb window makes much more difference in CBL, since it's very much based on getting ll thew carbs in withing a few hours of a workout. CN is more about spiking insulin/blood sugar, and refilling glycogen. a long window wont do so much more damage than say a 2-4 hour window. As long as your first meal of the day isn't super high GI you should be fine