These trees are at their best if you train them to between 4 and 6 ft. tall before you let them branch out. This is sometimes hard because you will have to cut off side shoots that may have buds on them, but if it branches out too soon it may never reach a suitable height. Constantly train your tree up a support such as a bamboo pole. Tie it to keep it as straight as possible. If a branch grows out of control in the wrong direction, just let the pot dry out a little more than usual and the branch will be come very flexible. Tie it up straight and then water. It will harden in its new position.
The reason for growing it so tall is to appreciate the flower. It is best to have the blooms at eye level. If you let it branch out earlier it will still be quite beautiful but the blooms will be low and hard to see .You will also need a lot of space as they can get very wide. Six feet or more in one season is not unusual.