I’m looking for some advice on this Trident Maple trunk chop. I recently acquired it, and it is pushing new growth at the chop point.
Should I let all the shoots grow for now, and reduce the number later, or should I reduce the number of shoots now?
This is the first trunk chop I have had, and the first Trident Maple.
Any advice will be appreciated. Thanks! 
Wait for that flush of growth to harden off before considering any more work. Once the tree is energy positive you can determine if growth was vigorous enough for pruning. Personally, I’d wait until Fall before cutting anything off.
Since its new to you its hard to say how strong the tree is at this time. A trunk chop is a pretty drastic thing to do to a tree. If its done at the right time the tree will recover in time. If at the wrong time you can really set a tree back or even kill it. If it was mine I would also wait till fall to prune again. You should watch your tree and make sure it grows well this season to confirm it is strong enough to work on next steps. If knew that it was vigorous and planned to keep the new shoots I might lightly wire the new shoots then wit till fall to prune.
Let it recover. If one branch is becoming the leader and you’d rather another branch accumulate the strength and lead you can 1) wire the branch you want stronger up, and the other down or 2) once shoots harden off you can let the desired longer/stronger branch grow and snip the other one back to 1-2 sets of leaves.
