https://wccftech.com/microsoft-device-is-ready-for-windows-10-1903/

Wondering whether you can upgrade to the latest Windows 10 May 2019 Update? Microsoft is now letting users know if their machines are ready for the upgrade. The following message appears when you click on check for updates button in the Settings app:

The Windows 10 May 2019 Update is on its way. We’re offering this update to compatible devices, but your device isn’t quite ready for it. Once your device is ready, you’ll see the update available on this page. There’s nothing you need to do at this time.