Get Familiar with Android 8.0 & Android 8.1
Samsung hasn't released a Galaxy S7 Android 8.0 Oreo beta and we don't expect the company to extend early access to the Galaxy S7, Galaxy S7 Edge, or Galaxy S7 Active. So unless the update leaks (and there's a chance that it will) you won't be able to try Android Oreo until it's officially released.
Don't wait until the official roll out to get familiar with Android 8.0 Oreo. It's important to get familiar with a new operating system well in advance. That way, you aren't caught off guard by any of the changes on board.
We don't know what the Galaxy S7 Android Oreo update will look like, but if it's anything like the Galaxy S8 version, it'll come with some very noticeable changes to the user interface.
You'll also want to make sure you get familiar with Android 8.1 Oreo which is the latest version from Google.
Samsung is currently testing Android 8.0, but there's a chance some of the company's Galaxy S7 Oreo updates come with changes from Google's Android 8.1 update.