That was me. Season 12 first premiered on Nine on 16th October 2018, so Netflix Australia gets the SVOD rights exactly 2 years to the day.
I remember when Season 11 became available on Netflix Australia on 17th October last year, which was exactly 2 years to the day when Nine first premiered the season.
With that in mind, that date would also mean that the FTA rights to S12 would be transferred from Nine to 10 (where Seasons 1-11 is already there). For instance, when Seven picked up the repeat rights to Seasons 1-7 in 2015, they didn’t get Season 8 until October 2016, which was when Nine’s 2-year exclusivity to the season had expired.