As someone who grew up in NSW it's 14 and 9 months. Exceptions might exist for family businesses etc. but your 8-year-old can't apply for a job at Woolies.
Apparently it used to be that, but now there is no limit: https://www.industrialrelations.nsw.gov.au/new-to-work/essential-information-for-people-new-to-work/new-to-work-faq/#:~:text=How%20old%20must%20I%20be,may%20apply%20relating%20to%20age.