While you upload your event content to your organizer dashboard you will be able to view this content in your app immediately. For those listed as admins for your event (Attendees > Admin Settings), they will be able to view your event in the app even while the event is still in draft mode. Make sure to log into the app with your admin email/account.
Your app will look the same as an attendee's app with the exception of the 'admin' section. You can also click on the ‘Preview Web App’ button to preview exactly what your Web App will look like to your attendees.