The JBP is way to young and undeveloped for needle plucking as River stated.
The white pine, while a bit older is still a young and undeveloped tree.
For now the best thing is to water and fertilize them.
In the fall wire and put some shape into the JBP's trunk.
The white pine has a lot of its branches with foliage out away from the trunk and not much close. I don't know how well they back bud on old wood. You should research what others have found with them and if they have successfully gotten them to back bud. If so, follow their techniques with this one. If you can't find info then research techniques for single flush pines (Japanese white pine, Scots pine) and try those