Did you preorder The Sims 4 on Origin? You did? Great, because you can official start preloading the game, that is, downloading it in advance and get it unlocked on the release day!
This doesn't mean you can play right after downloading it, but that you can download it before the release so you won't have to wait on the release date (even because it's ~9GB in size!)!
Speaking of Origin, I'm sharing a link that not everyone's aware of: like any other retailer, Origin gives its customers the chance to get a refund if they don't like the game. It's called Great Game Guarantee (and The Sims 4 is part of that): you have one week to download the game and 24 hours to play it before asking for a refund. More information here: https://www.origin.com/great-game-guarantee