On April 22 2018 the latest OmniROM update for Redmi Note 4 (mido) was announced on its XDA Developers Forum thread by khan_frd2002.
The update was available directly from the download centre or as a delta update via OTA as demonstrated in the full length video below:-
The video above after a brief introduction to the OmniROM features actually shows what stage of the delta update process takes the longest time to be completed. 💦
It also shows the result of the process after flashing in the last one minute and thirty-five seconds of the whole screen-recording. 🎞
This OmniROM Oreo delta update was flashed using latest normal build of Red Wolf Recovery:-