Jetstar do not interline baggage with Qantas Domestic.

http://www.jetstar.com/au/en/Plannin...ht-Connections

In any case, if you are checking bagage, you would be SOL.

Without checked luggage and assuming you are scheduled to arrive at 11:20pm and hope to catch the Noon QF flight to SYD, your chances are slim.

Required events:

• Gate to Immigration (Hope the gate is a low number - at can take 10 minutes)
• Immigration (Hope the queues aren't big; it can take 15 minutes easily)
• Customs (Hope you get to go stright out with nothing to declare - can take an hour)
• Walk to Domestic
• Security
• Walk to Domestic gate (Hope for a low numbered gate)

At best that's about 25 minutes - the door should close at 11:50 giving you 5 minutes leeway.