Download and install the Windows 10 Spring Creators Update using the Update Assistant
After April 10 you can upgrade to the final version using the Update Assistant tool, go to the Windows 10 Update Assistant webpage and choose 'Update now' button.
The tool will download, then check for the latest version of Windows 10, which includes the Spring Creators Update.
Once downloaded, run the updater, then select 'Update Now'. The tool will do the work. Your PC will restart a few times, so save any open files first. Your PC will update to the Spring Creators Update, all your data, Programs and settings will be unchanged.
Note, this will only work once the Spring Creators Update is officially released.