I can help with an answer.
NBN has to be one of the hardest companies to get to speak to a person. Most of the choices when you dial them point to their website.
BUT I persisted and spoke yesterday to a very helpful lady. I had specific questions about an apartment block.
When they say that you are NBN ready, it means that NBN is available in your street.
In normal circumstances the cables (for apartment blocks its optical cable) and the termination equipment should be installed by NBN. I was told that there are reasons why sometimes it is not (some of the reason she were pretty lame and explains why NBN is costing so much).
I was advised that despite the termination equipment not being installed, one should contact your NBN provider of choice and place an order for your new service. The provider will come out and discover that the termination equipment is not installed. They then ask NBN to come back and install the missing equipment, and all will be good.
I haven’t tested this yet, but seemed plausible.