The following is a link to CASA's pilot log book page. The way I read it, as a second officer you can log the time from push back to on blocks, but you cannot log the time spent resting.
https://www.casa.gov.au/standard-page/pilot-log-books
Relevant quotes:
Flight Time (Aeroplane)
means the total time from the moment an aeroplane aircraft first moves for the purpose of taking-off until the moment at which it comes to rest at the end of the flight.
Note: This is synonymous with 'chock to chock', 'block to block' or 'push back to block' time.
Operating Capacity and crediting of flight time
Co-Pilot Includes all flight time as co-pilot or second officer. Time spent as designated crew rest during a flight CANNOT be credited towards co-pilot time.
Note 1: only 50% of the flight time logged as a co-pilot can be included for the purpose of calculating total aeronautical experience.