These are nice, you should think about cutting the fatter branches back as they seem a bit heavy for the trunk, that is if you're happy with the trunk development as it is.
It's pretty easy, Japanese larch throw a lot of material out each and every year to work with. Once the shoots lengthen to about 1.5 inches or more, prune them back to about a third of their length. You can pull needles off the bottom of the branches to keep it neater. You may need to pinch more than once, as they can really shoot out.
You should try to keep your pruning towards the early season, late pruning can result in large coarse knuckles. You probably know about repotting, if not, make sure you repot before the buds pop all the way. I do mine when they look like tiny shaving brushes. If you do it after that you risk the tree.
The Colin Lewis article in Bonsai Today issue 79 available at Stone lantern (cheap) is well worth the cost, and lays out pruning for bud selection step by step, and better than I can describe it. Dave Joyce's book "the art of natural bonsai" also has some decent info for larch.