The last person I know who tried to apply for a c of v ( special licence takes just as long) from overseas gave up after nine months. CASA only took a couple of days to take their money though
One of the biggest problems is finding someone overseas that CASA will approve to verify your documents.
The irony is that an overseas pilot doesn't need an ASIC to be able to fly here however they are supposed to have them to go into a security controlled airport...but I know of some where they haven't got one and OTS have just overridden the airport security people who have pinged them and let them get away with it.
Good news is that under the new changes which may finally drag Australia one step closer to ICAO there will be no need for CASA to be involved and all the paperwork will be done at the flying school that does the flight review. This could be another few years away though.
I wish it was different as Australia used to be a wonderful place for visitors to come and fly and it was a valuable part of the tourism industry until CASA and OTS stuffed it all up for no good reason and without any consultation. ( note to CASA, a fait accompli is not consultation) good luck.