If you decandled, that means you’re in the refinement stage of JBP development. So, pull all the old (2017) needles. This opens the tree up to allow sunlight in to keep interior foliage alive. Also makes it easier to wire. Go thru all the new summer candles and where more than two new candles grew, thin to two. Then wire. Wiring will open up the branches, allow more sunlight which promotes backbudding at old joints.
If you did not decandled, this means you are still growing. Old needles provide more solar panels (food) for the tree to grow. Remove the downward facing needles, and thin the rest of the old needles to where you keep 1/3 to 1/2 of the old needles. Keep a pair of needles where you might want a back bud to pop. No guarantees, but sometimes a “needle bud” will pop where you leave a pair of needles. If you see a place that has 3 needles, it WILL pop a bud! Keep it if you want a new branch there. Remove it if you don’t.