I know when we get the Pokémon Sun and Moon demo in the Nintendo eShop in Oct. 18, but I wanna get it as soon as possible. When is the demo available?
Well, there is no earlier time to receive the demo - and each time zone and country seems to have it on the same set date as well. Therefore, October 18th, 2016 is the earliest for the demo.
Hope I helped! :)