The April 2018 Update is available today if you go to Windows Update and manually check for updates.
We will begin the global rollout out via Windows Update on May 8. As with previous rollouts, we will use real-time quality feedback to smartly update your device when we have data that shows your device is ready and will have a great experience. You don’t have to do anything to get the update; it will roll out automatically to you through Windows Update if you’ve chosen to have updates installed automatically on your device. Once the download is complete and the update is ready to install, we’ll notify you, so you can pick the right time to finish the installation and reboot, so the update does not disrupt you.
Jim 