Wrong branch, Masonic Phantom, as this is the VA/VFF side.
But... as soon as you have done OLCI, just go to the F counter to get your passport spied on their special keyboard at check in, telling them you have done OLCI/they might already can see from their screen, then try to get past immigration and international security processing asap.
My first MEL QF F lounge, the plane was an EK 380 though, I was able to get into the lounge by 6.30am or so, the frosted doors were open for the first EK flight to DBX, but were locked again when I was waiting in line to fly to AKL.
But I was in the MEL QF F lounge for about 45 mins or so, then off for boarding about 7.15 am.
You don't say if you are flying the first EK plane out to DXB (checkin at 3am for the 6am flight out), or the soon to stop EK plane to AKL, or the new QF 380 route MEL - SIN - LHR.