In many countries, Android Oreo update for Samsung Galaxy S7 and S7 Edge is still not completed. It would take some more time. This time span might be few weeks or months. And then these Android Oreo 8.0 software updates would be installed on all devices. A few months ago, Samsung was forced to stop the release of Android Oreo Update for Samsung Galaxy S7 and S7 Edge. Some bugs were the reason behind that. It has been resumed. You can download and install it.
Install Android Oreo Update on Samsung Galaxy S7 | S7 Edge