AT&T kicks off Android 8.0 Oreo rollout for the Samsung Galaxy S8

Although AT&T has yet to update the Galaxy S8 and S8+ support pages, it appears that many redditors have already installed Oreo on their smartphones. Speaking of the update, if you're an AT&T customer, you'll need to make sure you have enough storage since you'll have to download around 1.55GB.
You can manually check for Android 8.0 Oreo by heading to Settings / System update, but don't fret if it doesn't show on your phone yet. Since this is a staged roll-out it might take a few days to propagate to all AT&T Galaxy S8/S8+ devices.
source: Reddit via Droid-life