That's excellent Cian!
Yes, Police certificate (PCC) is the next priority. I didn't apply for it until I received my nomination. But some of our friends here advice it is better to consider it before nomination. But you need to be sure about the validity of PCCs. Some countries' PCCs are valid only for 3 months from the date of issue. I mean, after nomination, at ITA stage, when you finally submit the application to CIC, the PCC should't be old, say like only few days to expire or somethin like that. CIC will consider all PCCs that are not older than 6 months at the time of submission but PCCs itself will have validity. And countries differ in it.
As for your Aussie stay, I think you'll have to give PCCs for all countries you've stayed for 6 months or above. If you were under 18 at that time, you don't have to give PCCs for that.
Keep medical under radar! Sometimes appointments are tough to get. But the best advice is to do medicals as close to the time of submitting final application to CIC. Once medicals are done, you will have only one year from that time for landing in Canada. So keep it last, but prepare and keep everything ready - I mean Panel doctors in your locality, appointment etc. If you've given paper based application to CIC, then I think Medicals should be done at CIC's request. If electronic EE, you can do an upfront medicals, which is the most preferred method.
So, what next?? Next is Nomination bro!! NSNP will do it! It takes about two to four weeks from your AOR reply.
All the best,
Luder