As of 8 May, 2012 the government removed the ability for non-residents to be able to claim the CGT discount post 8.05.12.
As such, it would be prudent to obtain a market valuation of cgt assets such as real estate at 8 May, 2012, as they shall be entitled to a CGT discount until this date.
Careful planning would also be needed around selling, particularly if you are planning to return to Australia.