The routine with foliage is let it grow until about August (or, more universally, about 6 weeks after the summer solstice), then cut back to a bud. Any branchlet without a bud is as good as dead even though it may not loose its needles for another year or two. So, back to a bud or to a node (where a branch jumps off the stem or from which this stem originates). This will induce back budding, even on the old trunk.
Some individuals recommend that you pinch emerging shoots - that is, tug off the top third/half of the emerging shoot about the time you can first identify needles. I suggest that you do NOT PINCH. It is a technique for limiting the length of new shoots that may be applicable to maintenance of a 'finished' bonsai, but does nothing productive in developmental phases. In my experience the technique does not reliably induce a second flush. In fact, second flushing seems to happen, regardless, with a healthy, vigorously growing tree. Obviously, you can try it yourself on your tree over the coming years.
They can be bare rooted, but instead I suggest that you only remove the soil from one side of the trunk (known as 'half bare rooting' or 'HBR') in a season. This can be done in spring as you see the buds swell. I prefer to repot around August. When I do. I postpone cutting back to a bud until October or the following spring. as the new foliage will power regrowing roots to recover from the damage of repotting.