The update assistant for Windows 10 creators update would be released on 5th April, says Microsoft
The primary date on which Windows 10 creators update would be released would be April 11th, where it would be available through Windows update. As Microsoft said, it would first be available to the devices manufactured by its partner OEMs and then subsequently to other devices. Also, many other factors like location, configuration etc affect the availability of the update on your device.
For those who are eager to get Windows 10 creators update, an upgrade assistant would be released on April 5th which can be used to Install the creators update. Remember this is only for advanced users.
For businesses, you can ask your IT administrator about when it would be deployed to your organisation.