@richardparker
If you want a clean installation, you can install the eshop copy (using CDN-FX) right now. On 18th there will be released a seed. You have to import this seed on 18th using FBI.
This is the most clean installation you can get.
Another option is installing the leaked cia from that iso site right now and open the game after 18th (You will probably have to visit the eshop again, when the game is released).
Does anyone know, when the eshop version will be playable for Australian people? Is it on 12am Australian time? How was it in the past, were eshop games released on midnight?