What is the question here?
As far as we have observed - the apps sent to Sydney is sorted(in whatever god only knows way) and is checked for completeness and processed. Once the application checks off on completeness - AOR email(or mail) is sent out. The processing of the file from this point onwards is done by the local office(based on applicants residence)
The local office will conduct the test and interview based on their capacity. The schedule for oath is also based on the local office capacity. I think that is what
@ZingyDNA mentioned as "Once processing starts, your local office will matter." Once the local office starts processing - ECAS would indicate "IP".
This is my understanding;