Hi!! I'm waiting, too. I'm originally from Michigan, USA, and we didn't do a 300 first--I was in Australia on a work and holiday visa for a few months before we decided to get married. My husband and I have been in a relationship for eight years, so we knew we were going to get married eventually. A work and holiday visa made the most sense when I applied, but a variety of factors ended up changing "the plan" to get married later, so we ended up eloping and applying for this visa.
I applied back in March, but without the police checks or medical completed. I've been having horrible difficulties getting an FBI police check done. Money just left my account for what I hope to be my last application. Hopefully it turns up soon so I can get it in! (My Australian police check came within a week.) When the FBI check shows up, I'll probably go ahead and get my medicals done. I know the results are only good for a year, but as it's been eight months for me now, I doubt it's going to take another full year to process my application--fingers crossed, anyway.
When I was filling out the application I was stressing about having enough evidence and I was really nervous about forgetting something or not including enough. However, months down the track, my only real concern has been about getting this police check in and doing the medical (there's nothing wrong with me that I know about, but I really don't like going to the doctor! Completely irrational, I know). Another worry was about my husband, who is my sponsor, not making enough money as he was in a part-time position when we applied, but he's working full-time now and in a higher wage bracket as well, so no more worries there. As for other evidence, I've gained more confidence in what we turned in and have decided not to let it stress me out so much.
It's so nice to hear from other people who are applying for the same visa as me! I hope everyone gets theirs granted soon.