Call your local Police Station and ask for the firearms licensing officer, organise a suitable time for him / her to come over and do an inspection. Once done, ask them to txt / email you the "COPS" Event number, record then number and put it in your files with the rego papers of firearms owned. This is how I did it when I applied for an ammunition purchase and sell permit. The officer turned out to be a keen shooter, spent 10 mins on the inspection and the next 2 hours talking about shooting and hunting. Ask questions about what they think of your security setup and if they have any advice.
As there's no requirement to have your storage inspected prior to storing firearms they may very well decline to perform an inspection. You'll get added to the schedule of inspections at some later date which is a random number between 4 weeks and never
Personally I would like to see a proactive approach to securing firearms in NSW in that you need the "COPS" event number for the inspection listed on you application for a PTA so there's proof that you have the required storage for the category of firearm applied for.