If you want to set up a quick demo project with React Fiber you can use the create-react-app way and simply:
npm -g install create-react-app create-react-app fiber-test cd fiber-test npm run eject npm install react@next react-dom@next npm run dev
Which will install
react @ 16.0.1a3 at the time of writing
If you want to try out react-fiber in an existing project simply use:
npm install react@next react-dom@next
Be cautious of bugs, although the cool big chart says, we’re almost all good/green to go. 😉
If you want to know more about fiber, I suggest you watch the video below, it’s kind of awesome and talks about scheduled/bulk DOM updates.