Your profile shows you are based in Brisbane. So assuming you are taking a BNE-MEL connecting flight to pick up QF9, you will be checking in nice and early for the QF9 flight. But if you are starting in MEL on that day, then I recommend being at the airport at least 3 hours early. You have Qantas Club access, so enjoy the lounge and "prepare" for the flight.

When you check in, ask how full the flight is today. And if its not too full ask if they can find you two seats in the DEFG range with nobody else in the row. I would always take a D or G aisle seat over a C or J aisle seat.