Ponderosa Pine Saplings

Hi folks, I'm growing some Ponderosa Pines from saplings out in the garden. They are about a foot tall and several have limbs (some do not) down low on the stems and I want to cut the stems at this branch. Can I do/should I do this now or wait for a few years for trunk development. I'm afraid these low branches will die back as the trees grow upward. Thanks for your thoughts on this.

Here's a pic of my little pine.
The branch at the bottom is where I'm thinking of cutting