Last year I was going through the bees mid February. But it was very warm, they were flying strongly. But generally an 'inspection' would be simply how much space do they need, is it enough and here is some more (if they do) affair. Bear in mind though, that winter was only about 6 or 7 weeks long, last year......
Temperature is certainly not the only parameter to consider. Wind, precipitation are another couple. No chance to do so much more, excepting maybe uniting colonies, if necessary. One risk of early interference is 'balling of the queen' which I have not experienced and do not wish to encourage. As Finman said, inspect what?
Dartingtons are so easy in this respect - no greater need than sliding the frames forward with them; only removing one half-size coverboard; no risk of splitting the broodnest horizontally; just increase the broodnest by a couple of frames if necessary and close it up. Very little disturbance. A bit different to a standard National.
So other considerations are: will this benefit the bees? What could you do if you found anything untoward? No and not a lot, is the likely answer.
Regards, RAB