I'm a bit late here but as someone said , can't remember who ATM, I also re-pot mine around July 4th. I use to re-pot mid to end of July but where I am the weather cools too early to get good growth before they come in for the winter. They like to stay above 70 deg after re-pot for 4 weeks or so. I also defoliate the trees but leave the petiole, doing this also encourages back budding. Been doing this for 26 years or so. They seem to have no issue with massive root work when doing this. I also mix in about 5% chopped Sphagnum moss but they seem to grow in just about any bonsai mix.