T-Mobile 's Samsung Galaxy S8 and Galaxy S8+ are updated
So you tell us that you haven't yet received the latest update for your T-Mobile branded Galaxy S8 or Galaxy S8+? You can try to arrange for the update to be manually coaxed out of your handset by going to Settings > Software update > Download updates manually.
When you receive the notification telling you that the update has arrived, before you begin the process of updating your device, make sure that your Galaxy S8 or Galaxy S8+ is connected to a strong Wi-Fi network. At the same time, the battery on your device should be charged to at least 50%. In case you're curious, the size of the update is 418.5MB.