My larch are always wired and styled (and transplanted) before they have budded out mostly because it is vastly easier but also because the new buds are pretty fragile in the spring and the wood does not like being jacked around. If you must wire wait until it has hardened off but I would not bother and would work on other things.
If your planning on entering your larch tree into a state of refinement within its basic form I find that they cannot have such a unrestrained set of roots and need to be down potted even if growing out. I would grow it well this year and strengthen it with a late summer fertilization, one could craftily tie down a few important branches in the meantime. Next spring, while dormant, I would select and set you branches with wire--wire everything, And also root prune and down pot it at the same time--be brave. Then don't over fertilize, the common larch-in-refinement mistake, and keep wiring.
If you have wild fantasies about transforming this larch into a beefy thing your path will have to be wholly different.