I made this in a week, just launch and got my first $100
I dont know if you can make an app in a week, in my case I ported my macOS version into iOS, the core logic is shareable that is why it only took me a week.
Coming from macOS I need to rework on the UI completely, especially UX because tiny screen of the iphone, so far so good.
It took me 11 days to got the app approval (apple review app quite slow these days)
For marketing I share the app very early, on the first day, first demo I share it on my social accounts (X, Threads) and got quite a lot of views
If you share your app recording on iphone, can take a look on my apps, if you have any suggestions please let me know in the comments