Late Spring and Summer is when I prune and re-pot most of my native bonsai at Shibui Bonsai.Many Australian natives seem to resent root disturbance in the colder months but just continue to grow when I prune roots anytime during the warmer part of the year. I find that younger banksias in particular grow masses of very fine roots that quickly fill the pots. If left for a few years the root mass gets so dense that it is difficult to water and trees have died as a result. I now re-pot banksias, and many other native species, every year or 2 with much better results.
Here are some photos of re-potting a young banksia, callistemon and a series showing the steps re-potting a ficus.