Oh good old Mildura, I lived there for a while a few years back fruit picking, I lived in Redcliffs. In the acknowledgment that they received my application it did say that the case officer would contact me once one has been allocated to me, although I have heard of people not knowing they had one till they were told the visa was granted! I'll keep you posted when I hear something. My app is lodged at Paramatta which has the biggest backlog at present it would seem, Melbourne are supposed to be pretty good, my agent said she has had some be turned around very quickly (weeks rather than months) there. As far as I can gather if the nomination has been approved at immi then you have a CO and the same case officer should deal with the 3rd stage. Good luck too and keep us all informed with your progress!