Hey buddy, welcome
Yes, I would definitely submit my PTA at the same time as my application.
(That will save you 1x month of extra wait time)
From what I understand, you can download the PTA form online from the Victoria Police web site.
Once you download the PTA form, print it off.
Then, take the PTA form directly to your gun store and get them to fill it out for you.
Once the PTA form is fully filled out by your gun store, when you go to send off your physical final application (in hard copy) in the mail, simply attach your PTA form all filled out at the back of your application and then post everything together in the mail in the one go.
That's it