If you want the Spring Creators Update immediately, you can force the installation by following these steps:
Once completed, you should be upgraded to Windows 10 build 1803.Right click the Windows button and open "Settings". Select "Update & Security". Click on "Windows Insiders Program" Following the on-screen instructions and when it prompts you "What kind of content would you like to receive?" you need to select "Just fixes, apps, and drivers".
Note: When the installation is done, you need to stop the Insider Previews to prevent the installation of further pre-release builds.