I agree that it's not worth predicting it, be prepared for whatever exam is thrown at you.
The 2012 exam was written before the students sat he 2011 exam, hence it doesn't have an influence.
On this, here's a document that gives a timeline
https://www.ssms.vic.edu.au/ASR_Link_Files/2013%20SETVET%20info%20kit%20v1.doc. This has been updated for 2013, but I'm confident that the document was pretty much the same for the 2012 exam timeline when I looked at it earlier this year (and would suspect that it's been the same process for years).
What your teacher said about September in the year earlier is just getting the people together, they don't start writing the exam until a bit later. But yeah, they do start working on it early, with a first draft done by Feb of that year.
A general timeline
August/September (2012) – formation of panels
October – Panel Chair briefing
February (2013) – first draft of paper submitted
March – first vetting checks underway (Study Specialist vetting)
May – desktopping and ESL vetting
June – second vetting checks underway (Sitter vetter, Teacher vetter, other specialised vetting if required)
July – signoff by panel
September – examination printed and final QA checks by panel.
This is a guide for the November written examinations only; it can vary markedly from one examination to another. It is always assumed that the paper will be completed earlier than this timeline.