Samsung will soon launch the One UI beta program for India. As it is the FOTA update it is difficult to tell what date and time it will hit your device. Keep checking your notice in member application, it may happen anytime now onwards.
The beta will be available for the Galaxy S9, Galaxy S9 Plus in certain countries this month including India. Samsung plans to release One UI in early 2019 probably January 2019.
Once you log in, go to Notices and select One UI Beta Program Registration to submit your application.
If you are selected, go to Settings and then Update Software to pick the Download Updates Manually option. From there, just sit back and wait until the One UI beta version downloads and installs on your device.
After finishing all these steps you are ready to enjoy all new UI.
