Myself, Where I wanted to bring growth in closer to the trunk, where I wanted to shorten branches, sometime after the summer solstice, I would prune new branches back to an existing bud. Buds will form on new growth, you often won't be able to see them until middle of July. Sometime in the summer, in my location between July 15 and Sept 15, I would cut back to the buds in the middle of the new growths. If there are no buds, don't cut back. A branch without dormant buds, if you cut the terminal the branche will often just die.
So always make sure to cut back to existing buds. That is the bulk of spruce training.
When the tree is mature, some 20 years in the future of the tree in your photo, then you can start "pinching" instead, but that is many, many years awady.