@kholoudmanlucu hmm... lemme break it down, eto ung available information sa grant letter (assuming grant was March xx 2016):
Initial Entry Date = usually, eto ung date whichever is the nearest na mage-expire (police clearance, meds exam, passport). kunwari Feb xx 2017.
Must not enter OZ = aka, "expiry" ng visa. eto ung 5 years after the grant. kunwari March xx 2021 (5 years after the grant).
At any given time, between your IED and Must not enter oz dates, pwede ka pabalik balik ng Australia, walang limitation.
Yung kelangan mo lang i-take note is that once the visa expires, either converted ka na to OZ citizenship or ibang visa na ung kelangan mo i-apply (RRV = return resident visa, which is meron siyang rule bago ka ma-grant / usually must have stayed in OZ for two years within 5 years)