How do you get started with nothing?
A blank page, a basic idea, and an early MVP. That is how it starts, and it is not exactly nothing. But that does not make it a company, or an app, and it certainly does not come with customers, unless you have a really convincing MVP or a great production-solution fit.
The chicken and egg problem
Depending on the type of app you are developing, sooner or later you will face the famous chicken and egg problem. Simply put, an app that depends on user-generated content will have no content without users, but also no users without content. So, where do you start?
Any marketplace-based app has to deal with this challenge, whether it is an app for dating, job finding, or bringing companies together. But it does apply to other types of apps as well. There are many apps available in the App Store. They all are doing more or less the same thing, so why should your users (and later, your customers) use your app and not any of the other apps? Sooner or later you need...