dragonfly53 , being in 8a (Va.Beach) myself I know it is more challenging to grow plumerias here. You are mostly going to get branching from blooms or damage/removal of the tips. Even then it doesn't guarantee branching. Here's a pic of one that has bloomed 3 times without a branch. Luckily it is not a tall grower.
Here's a tall NOID that bloomed in Dec. and I'm hoping it will hold the buds until I get it out in the sun and bloom more. It has 3 new tips but is on it's way to being a tallllllll tree. I may have to cut the top off and root it down the road.
Here's my very thin/tall Pudica. I've been threatening to cut it if it doesn't bloom and I'm almost to that point. I'll root the top and if there is a bloom in there, it might bloom while rooting. The center cuts(stem) should send out new tips too and also what will be the trunk which will already have roots.
I'm just not sure how to go about rooting such a thin cutting. If it sits for a week or two to callus I'm afraid it will dehydrate.
Plumerias didn't read the books and they do as they want. Some just grow tall and some don't. Like Hetty said, give them balanced formula and lots of sun and they will reward you with the blooms. Plumerias are great for teaching patience and hopefully the blooms will come sooner than later. Peg