After a really long wait, the official Android Oreo update for the Galaxy S8 and the Galaxy S8+ has begun its rollout. Beta testers in Europe are the first ones to get the new firmware, but regular users should start to receive it after 24 hours as well.
https://www.notebookcheck.net/Android-Oreo-based-Samsung-Experience-9-0-rolling-out-to-Galaxy-S8-flagships.281866.0.html