I usually thin excess buds on JBP in Autumn. The idea being to keep them all through summer while they are still growing which shares the available energy meaning none grow too big. Then in Autumn select which ones to retain - well placed, correct size for the location, etc.
It's still OK to remove the excess through winter if you haven't done it earlier. Leaving too many for too long may over thicken the branch.
You can also pluck excess old needles at the same time. Removing old needles reduces the foliage to limit photosynthesis which should slow down the strong growth and give better ramification and smaller shoots with shorter needles.
Is this a young tree? What time of year did you trim/decandle? Looks like the new buds have reverted to juvenile foliage and have not extended as they normally do after decandling.