Update: The roll out seems to have expanded. Reports say firmware version A320FLXXU2CRD4 for the model SM-A320FL is now hitting units in Germany, Austria, and Switzerland.
Following the Galaxy A5 (2017), which started receiving the update to Android 8.0 Oreo earlier this month, now the A3 (2017) is joining the fun. The update is currently rolling out over-the-air for units purchased from Russia.
As of now, it seems that it hasn't made it to any other countries, but that is unsurprisingly going to change in the future. It might take quite a while for this rollout to become global, however, with Samsung's Turkish arm anticipating a release for the A3 (2017) in June. Hopefully other markets will be more lucky.
If you have a Russian-bought A3 (2017) and haven't yet seen the update notification, you can go to Settings > Software update and manually check for the new software. It comes bundled with the April security patches.
It's interesting to note that the Korean company's 2016 flagships, the S7 and S7 edge, still haven't received the Oreo update, while mid-rangers such as the A3 (2017) are treated more favorably from this point of view. Oreo for the S7 pair should apparently arrive next month, according to the latest information once again coming from Samsung Turkey.