Under the Screen1 block section, in the When Screen1. Initialize event you can add a block open another screen with screen name Screen5 as a parameter to it.
So when your app initializes, it will automatically take user to Screen5.
And from Screen5, you can provide navigation to another screens according to flow of your app.
A tip if you want - I suggest you to use layouts instead of arrangement, because in case if you fail to switch the screens correctly, then you may encounter OOM errors.