Yamadori: Initial repot & styling
EXCERPTS FROM RY2TREE2
General Protocol for Yamadori Initial Bonsai Training
If the plant is obviously healthy, you may prune the plant back in the fall to get rid of unwanted branches and to shorten the branches you want to keep. Plants that did not have much new growth or new backbudding are not yet vigorous and should not be pruned yet! Wait until you see signs like this.
If the plant is obviously healthy, you can repot the tree in the first spring after collection to reduce the rootball and plant it in good bonsai soil. A partial bare root is the conservative method which is least risky for the health of the tree, but on small or young specimens, or certain species, a full bare root may not harm the tree and allows you to most quickly get rid of the native soil which is overly water retentive. Again, save the fine roots as much as possible. The first repot is a very delicate operation on an old yamadori!
Enter a cycle of periodic pruning and wiring of the branches to fit your design of choice. Again, do these mainly on healthy trees. If the plant is recovering from a bad year, it may help to let it grow out and prune it back again later!