A little advice for you, and it might seem just a little nuts, but I think you’ll thank me in the end.
When you start making your app (now just to be clear here, I mean an app that is intended to go on the Apple, Google, or Windows app store), start by making a dummy app and immediately put the app on the store.
Google and Android both have beta programs that work excellent. You can make incremental updates as you develop it. Using the beta programs can get you feedback quickly and help you to focus on creating the essential parts of your app.
Windows might have a beta program you can use on their app store, I haven’t gotten there yet. They *should* have one.
One of the most wearying parts of making an app is cramming your time into it and just when you think you are done… Dang it! Forgot to make a hundred icons and feature graphics.
Publish to the app store first and use the beta programs.