Sydney T1 International Check-In Time for flight to Auckland

I'm on the 5:45pm Qantas flight to Auckland. One checked bag. Platinum status.

Is it possible to check-in in the morning so I can spend the day in the First Lounge?

I'm pretty sure SYD allows all day check in.

I flew QF73 to SFO on 10 Jul. TO was at 2155 but due hotel checkout I arrived at SYD INT about 1530hrs hoping to get into First Lounge early. Was told that the flight was not open yet and to try later at about 1630 or 1700hrs. I swear I had checked in way earlier on other flights to US but staff stated there was nothing they could do until "flight was open". I tried to google what "open" means but no luck. BTW, the checkin for Business/First was like a ghost town when I tried and the kiosk checkin for Economy was pretty bare also. I just sat in the First Class Check-in area chilling. I noticed a few more flowing into the BIZ checkin section and asked at 1625 and mircaulaously it was open then all checked in.

Though I used the Biz/first entry (Fast Track) to Customs Immigration, it was another ghost town and same for going thru security. There are new machines (new to me) at security on left side near fast track entry and it appeared that I was no longer required to remove anything from carryon bag. Sec rep stated the machines on right/far right still require removal of liquids, laptops etc. Hope this helps . CZ