I've got a brilliant larch that I potted and wired in March. After removing the wires a little late, it now resembles sideshow Bob's haircut from the Simpson's. No pinching was performed, so it grew pretty aggressively. I'd like to trim it but my concern is that it may be too late in the season to perform. Should I simply wait until next Spring to prune or can I reduce the new growth to a third? Thanks fo your help with this matter and regards.

You can prune a larch a few times a season.
Pruned mine 2months ago, and last week again.

I prune mine throughout the entire season.

I have pruned some of mine for the fifth time this year, last week so yeah, go ahead.