Maybe a couple days after or before or similtanious release.
I'm sure Larian wan't it so. Europeon Fans and US Fans can enjoy the game at the same time.
I think, you are right for the date.
But it's not a Larian responsability.
French store have cancelled pre-order.
Some people are quite furious and larian guy has spoken on the french board.
He is sad for the leak of communication about release date, but larian can do nothing. Because only the publisher can make a decision about releasing.
It's in the contract.
