This is a plant that I started and it is from seed of "New Yellow".
I had quite a few seedlings of this and let them go. They all grew with one central leader and a few lateral branches. This particular one grew a multitude of branches and I have never pruned it.
The branches tend to become a bit lax as in photo when on the dry side (as it was in this photo) and once watered they pick up and are quite tight. It has never bloomed.

My question to you is. Do you think that I should prune it or do you think it will ruin it's overall appearance?
I respect your opinions and it will assist me in making my decision.
Rick

Myself, since it's a seedling, I would let it grow as it wants until you see the first blooms. Then you'll have a better understanding of its particular growth habits and can decide how you'd like to shape it should the blooms prove acceptable.

My personal preference would be to leave it as is. It a beautiful specimen. I have purchased a few plants of Ebay that looked good in the pictures but when I received them, I was disappointed that they had been pruned. Now it's obvious from your multiple postings that you have a great deal of knowledge (which I have shamelessly borrowed from [ thank you]) and skill so if you prune it, I know it will still be perfect.