Literati work on Ponderosa pine

I watched Literati Design. I have a Ponderosa pine that is almost a twin to the one in the video. My question is can I do the same work/needle count reduction at this time or is it too early?
Teri

It’s too early now to do that work on a Ponderosa. You’ll want to wait until the third-year needles start to drop, probably in mid-September depending on where you are.

Do you have any pictures?