I had my yamadori limber and ponda. I believe Randy had them 1 year before selling.
I bought last spring.
Styled this last fall.
What would be the best safest or appropriate time to take it out of its pumice and into its next pot and soil?
Depending where you are you could repot now. I can’t say for certain as I am not in the US so someone else would be more accurate. But in general in the northern hemisphere it’s repotting time. And from memory I believe that Ryan had said that pines were amongst the first repotted at Mirai.
In case you haven’t come across it this may help as it was a ponderosa repot!
it depends how much it has grown since collection. Did Randy say how long ago it was collected? That may give a clue as to when to repot
Where’s the pictures? They should stay in pumice. There may be years of root system development before they’re ready for any kind of final potting in fancy pots. Don’t kill them trying to rush things.
Slow and steady wins this race, that is best and safest. If Randy had them a year, and you bought them last spring then by my math they have been out of the the ground approximately 2 years. If you styled them last fall, 6 months ago…then I’d wait until this time next year before thinking about a repot if they were my trees. I would want to see that they responded well to the styling and they were strong, pushing new growth Pictures and location would help.