PSA: Starfield unpacking times can slow your Steam pre-load, but you can help speed it up

gamesradar.com:

If you already have Starfield pre-loaded on Steam or plan to prep it ahead of its early access launch tonight, August 31, here's a useful PSA: it might take some time for Steam to actually unpack the game files depending on the speed of your PC's drive. That said, it's important to avoid the mistake of assuming your file is being overwritten, canceling the process, and then re-downloading everything from scratch.

Starfield early access will soon open for anyone with a pre-ordered Premium or Collector's edition of the game, but those with the Steam version won't be able to play the second it goes live at 5pm PST / 8pm EST. That time is when Steam will start unpacking the files you've pre-downloaded, and the speed at which it'll do that is largely dependent on the drive you have the game installed on. That means if you have a smaller SSD or a slow HDD, unpacking could take a fair bit longer than it would have if you'd installed the game onto a bigger, faster storage device. 

The TLDR here is: if you have Starfield pre-loaded on Steam and you own multiple storage devices, it's better to save Starfield to the one with faster data speeds so you can get playing as soon as possible. It's also worth clearing up some extra space on your drive even if you technically have enough room for the game download, if only to make sure there's no file overhead problem while unpacking. (Amusingly, people also struggled with this for Fallout 4.) Besides, let's be honest, you probably need to clean out that drive anyway.

Likewise, if you're confused about why your Steam version of Starfield still needs to download and verify files even after you pre-loaded the game, just know that it's normal and doesn't require any intervention on your part.