I think it's already determined how much of the cane is damaged, but... not all of the damage is immediately evident from the outside appearance of the cane. For example, brown pith can be evidence of winter damage and this often extends further down the cane than would be judged by the color of the bark. I do think if you wait too long to prune, some weak growth which is not sustainable may begin on the damaged wood. This surely is not in the best interest of the rose.

Honestly, when I've pruned it out it's just died back harder. I've noticed that sometimes I have the best luck with it when I'm super busy in the spring and the die back stuff doesn't really get cut back till late spring when there aren't any more cold nights. Some of the most succeptible to winter die back - like any relatives of GdD- I'll try my dangdest not to touch till May.

I've given up on roses that aren't cold hardy but if i remember correctly, the real damage didn't appear until april when the temps are in the upper 60's. So now i wait until then before I worry about it. Sometimes I think it's the alternate freezing and thawing that happens this time of year that is the real culprit.

I think that there are different kinds of black damage: some is just plain dead and won't get worse, but other will spread vigorously downward. The latter kind has active fungi (and maybe some bacteria) and can be spread by secateurs (I wonder if this is part of cweathersby's continued dieback problems because it used to happen in mine before I became more careful about cleaning my pruners as I cut.)

When the black is still flexible, it's bad. If it's just black and verging on brittle, the badness may be limited.

One other thing to watch for is signs of dessication on green canes : they look as if the stem is withered. I've never managed to rehydrate withered stems and I've really tried. Where they are withered and wrinkled (usually one year old or less growth), that's going to be dead and you won't get good growth there.

When to prune: First to get off the bad parts that can interfere with having a good spring growth
BUT
If you have a problem with rabbits with an addiction to rose canes, then leave as many canes as possible to serve as a stockade to protect new growth. Likewise if you're going to be tossing mulch on, again try to use what nature gave you to protect the new and very breakable canes

Sort of a ballance of trying to do no harm while not wearing yourself to a frazzle.

Sterilizing my pruners never seemed to help. But I've often wondered if the winter die back I see here isn't a totally different can of worms than what y'all deal with. I mean, isn't it too warm here to worry about all of that? If mine die back then how do any of you guy grow roses at all? And the succeptible GdG relatives don't just get bad due to freezing/thawing- it's like any temps below 60 after pruning could kill the whole dang plant over night. I've seen THAT over and over, and my method of don't touch with pruners till after spring flush is just about the only way I can grow them.
But after years of worrying myself over spring pruning, it's nice to discover that the easiest way out also grows the best roses!

CW, see if this year you can plot temperatures at which your die back becomes a problem/accelerates.

There have been some published studies that specify what fungal diseases thrive at what temp ranges (and when they muddle very slowly if at all.)