Also heard the inaugural flight will be in December, it would make sense i guess to do it on the National Day weekend, which is also the F1 weekend this year. But i don't think it will actually get actively used for some time after that.
Its massively overbuilt i hear mixed numbers but i think it's designed to handle something like 40m passengers a year. The current terminals handle much less than half of that number from what i understand they need to work out a way to make sure it does not feel like a ghost town once it opens.