Everyone who preordered the game should be getting an email from Bioware letting us know that the date quickly approaches. Preorder players will be able to gain early access to the game on the 13th whereas normal players will get access to the game on the official launch date – Dec 20th.
If you’re a preorder player, you can go ahead and download the game client and have it installed for your early access on the 13th. Click on the download link in your email. If you have any questions about the early access head to swtor.com/early-access.