It may be 15 feet tall before it starts to branch, if it ever does. How tall is the tree now? Measure it, let me know and I'll tell you how much to prune off.
It doesn't really matter. Just cut it off about 36-40 inches above the ground. This will cause branching at the cut. It will not take long for it to start branching. Any branching below the cut remove if you want a tree but wait to cut them off until the top branching is in full effect. If you want a bush just leave most of them.Will do as soon as I get back home.....THANKS