I have only been here 9 years and was waiting for someone with more experience. Since they haven't shown up, I would suggest leaving it alone. You will have a better idea about trunk structure next year. I believe that the general rule is to have an odd number of trunks; 3, 5, or 7. You can see that this gives you a lot of leeway, and you can always decide later.

I've seen them braided and they look kind of neat when they get larger. I don't think it will be shrubby later on. Think more vase shaped with several trunks. You can prune them up later on as they grow so you have a canopy effect. I've seen where people will plant them every 6 or 8 feet and then prune them up so they mend together above so they provide a wide natural shade.

Whatever you decide, PLEASE do not train them as a single trunk and then prune off all the branches every spring. Crape Murder, people call it. They'll survive it, but they don't thrive.

Wait until Winter. Pruning now will encourage new growth that might not survive the Winer.

Wect,
Give it about 3 good years of growing in before you do anything to it.
Not this fall, but next fall you should being to see how the frame is growing in more, its a little baby now.
If, by the third year, you notice branches rubbing across each other, you should trim the branch that is growing up into another branch off. That way the branch that was rubbing will heal.
You can tim in March in the Carolinas, before it really leafs out, that way you get to see the frame better withou the leaves blocking your view.

Thanks for your responses!