Hello, I saw this exact caterpillar while out on a walk near Mt Majura in Watson. My friend commented she thought it a bit early for caterpillars? thoughts?
If you run the cursor over the records on the Apina callisto species page, you can see the annual cycle of adults in autumn and caterpillars in late winter into spring. August seems to be the peak caterpillar month as the caterpillars finish their overwinter development and look for a place to pupate. There weren't any July records this year, but there were plenty in 2020.