In general, I don’t decandle pines for the first 6-10 years.
The primary exception to this is when I need to create new branches for the tree’s structure.
After decandling or cutting back into old needles and creating new branches, I continue to let the tree grow without decandling until the trunk reaches the desired size.
Based on the trees in the photo, my first question is how large you want to the trees to become. If they’re going to be small trees, I’d consider decandling as the current branches are all too big to work with. If you want to create larger trees, they could grow for some time without decandling.