This is the response I received from the Australian Quarantine & Inspection Service re arriving after hours. You are charged overtime rates on the weekend or Friday evening.
From the District manager of Quarantine in Bundaberg:- re weekend charging. If any vessel enters the port limits on Saturday they must be quarantine/customs cleared. The same goes for Sunday the exception being if you enter port limits after 1700 on Sunday with Q/flag displayed you can anchor at the Q buoy till Monday morning and be Quarantine/Customs cleared when the marina opens at 0800.
Please be aware that if you enter the port limits between 1630 on Fridays and 1600 on Sundays you will be charged significant overtime charges.
When in range contact Volunteer Marine Rescue (callsign VMR488) on VHF channel 81 to announce your arrival. They will ask you some questions and notify us of your ETA. Their hours are between 0600 and 1800. If you arrive outside of these hours you may anchor at the Quarantine buoy, located at 24deg 45min 57.95sec South and 152deg 23min 29.27sec East.
About the boat "Quinco"
Quinco is an Adams 40 skippered by David and crewed by the Admiral, Rose. Quinco is a wishbone cutter rigged sloop. She was built in Fremantle in 1978. Sailed to the Cocos Islands then moved home port to Pittwater, from there, onto Melbourne then we are where we are, cruising that is! Constructed from "Airex" foam core sandwiched GRP with a ply deck, she weighs in at 12 Tons. Powered by a Nanni 4 cylinder 50 HP diesel engine.