I know a professional blueberry grower.
He said: “You never ever cut back, you only cut out old unproductive branches at ground level, so if you cut you cut out the whole branch.”
Pot on now, as already said, while they are still in dormancy, they will soon break it.
If your bushes are young i wouldn’t prune them at all, they are not going to loose any roots anyway.
If you got them old and you see they will benefit for making them a bit younger, do it.
