I am actually in the middle of an Australian Partner Visa (temporary visa subclass 309) application. My Partner and I applied off shore, and we have just passed the 12 month mark. Realistically, I think you should expect to wait 9 - 12 months for an answer. We hired a lawyer to help us with our application because honestly, immigration law was a little overwhelming for me. The advice we were given was that overseas applications tend to take a lot longer than onshore applications.
Another helpful bit of advice I can offer you is that the Medical test the partner will have to take, expires in 12 months. My Partner had his medical a couple of months before we logged the application and it expired while we were waiting for an answer. He then had to retake the test, and wait for the results to come through which has increased our waiting time.