Samsung Galaxy A8(2018) was available for purchase starting January end. Samsung Galaxy A8 and Galaxy A8+ run on Android Nougat 7.1.1 out of the box. The Samsung Galaxy A8 (2018) and A8+ (2018) have been spotted on the Wi-Fi Alliance website and the device runs on Android Oreo instead of Nougat 7.1.1 which runs as stable version in all devices.
This shows that the device will receive the Android Oreo in near feature and unfortunately, we don’t have the time frame. As the update is in the final stage we can expect the update in a month time.