The April 2019 release is out now, and you are able to activate this in your environment in order to be able to preview the features. You are able to manage this update through the power platform.
From the PowerPlatform admin centre, you are able to navigate to view a list of your environments. I would recommend not doing the update to a production instance until you have thoroughly tested it in a sandbox – I would also avoid updating your development instance as once you have updated you are unable to roll it back.
From the environment list, you can click on the name of the environment you wish to update.
Next to updates if you select Manage you are then able to upgrade to the April 2019 version.