Here are my rules on repotting:
With a new plant, I feel its always best to repot it right away regardless of the season so you can check the roots and you know what condition the plant is in. However, if it is wintertime (non growing season) when you get the new plant, you should only repot it into the same type of media that it came from - not into a new type of media. For example, if the plant came in bark, repot it into bark - do not put it into
SH or leca.
However, with a new plant that you receive in the summer growing season, I think it is safe to repot it into either the same type of media or a different type of media. The reason for this is that during the growing season, you get active root growth, so it should be able to acclimiate to a new media. In the winter, root growth is slowed and the plant may not be able to adapt to a new media.
In general, you want to ensure that the plant will have at least 6-8 weeks to recover in its new media because it will go through a period of root death and regrowth, and this takes time. It also happens best during the growing season.
I've lost many many orchids bc I repotted into
SH from bark in the winter. Please learn from my mistake!!!
I hope that makes sense!
Becky