it your phone is unlocked EU/UAE/US version than it may take ages. Samsung historically doesn't care much about customers buying unlocked phones, just Google update delays for s7/s 7 edge, S8/S8 Plus and Note 8.
It used to be that the carrier versions are slower to get updates. that has changed. Samsung has become so slow and not interested in customer's feedback, that users are complaining in many forums about unlocked phones being abandoned, literally, except a few regions. now it is carriers seem to push Samsung to work.
We are not getting timely security patches, and you want Oreo. and may I tell you, remember my words, Oreo will be implemented so poorly that you will wish to upgrade to the S9+ with a proper new shell and oreo implementation. and s9+ will get new shell and properly done Oreo by December 2018. in short, forget it.
