At last our beloved device Redmi note 3 has got Android Oreo.
Although the build is stable(yes I meant it).
All the credits must be given to developers at XDA Redmi note 3 section

It's almost stable along with Agni kernel(link to thread is given below)!.
It's most good feature is the room can give best battery backup of 13hrs SoT.

It's made possible by using Agni kernel.
Steps to install Android O

1. Download the rom
2.go to your custom recovery
3. Goto wipe --> format data(take backup of all your internal before).
4.install--> rom file.zip

If you have any issues regarding flashing please comment below.

Bugs known
 
Camera Force close.(stock camera only, sometimes).
Notifications get divided into half (can't see content) only some times (rare).

Tip: this rom is almost bug free ,it is great for daily usage. It's the best initial build you can get .

Credit: all credit goes to the developer at XDA.

Download links. 

 Rom:- https://www.androidfilehost.com/?w=files&flid=210816
Thread link:-https://forum.xda-developers.com/redmi-note-3/development/rom-aosp-oreo-t3664605