Thank you for reaching out to the Samsung community! You can check for the Oreo update notification by using Smart Switch PC suite as well. You need to download the PC Suite from below link: http://www.samsung.com/in/support/smartswitch/
Note: Don’t disconnect your mobile phone from PC at the time of device software installation.
If still your device did not get Oreo update please visit nearest Samsung authorized service center for the software installation. Please find service centre details in the link provided -http://www.samsung.com/in/support/servicelocation
Be sure to hit ♡ when you find an answer that works for you. For further assistance, you can get in touch with us via Live Chat option by following- http://livechat.support.samsung.com/Customer_new/IN. You can also connect us via Samsung Members web community by following mentioned url-https://community.samsungmembers.com/en_IN#/