Truthfully, you could do it better to sit in whY from ADL if you HAVE to transit SYD/MEL/BNE on the flight from ADL to the eastern states before the big flight.
FIRST, option, if available, go via HKG.
Second option, if you still want to go via SYD, is to fly the 5.55pm flight from ADL - SYD, gets to SYD about 8.30pm, you can get the get a taxi, for 4 is not that bad, $30/4.
From T3 to T1, the distance is short, but the taxi fare is high, but with your luggage for 4, taxi will be best.
You could also get a bit of an earlier flight ADL - SYD, and get a bit of sunshine for window view, arr into SYD.
I assume your QF SC is Bronze, so you won't have any lounge access as it is, ADL QP (Qantas Club) is nothing special to crow about, nice to get a drink/basic meal, or you can have something at many of the eateries.
PremY does not give lounge access.
If you do successfully scoop 4 J award seats, this will give you lounge access all the way. SYD QFi J lounge is nice.