Premature customization and branding will cost you
When the first release of a mobile app being developed, it is very tempting that you want to customize all the user interface elements that the iOS or Android operating systems provide by default. You want to deliver a unique user experience. The temptation comes from the fact that every new startup or enterprise app is trying to appear well established. There is however an added cost when you do rich customization and branding prematurely.
A new mobile app will be going through many development cycles to be improved. The app user experience and user interfaces often need to be updated for every development cycle. This customization adds a time and cost overhead to every iteration of the developed app. If you are developing an app for a more fragmented market such as Android, then you have to test your customized UIs on multiple devices and for different screen sizes which further increases your overhead cost.
At least for the first 2-3 years of your app gaining user traction in the market, you can do without heavy customization and branding of your app’s user interfaces and instead stay with the default elements that iOS or Android provide. The best trick is staying with neutral and monochromatic colours (often white and shades of grey in iOS) and only adding one colour that represents your brand as well as your logo and app icon. Fortunately the recent releases of both iOS and Android operating system provide very minimalist user interfaces which allow you lots of room to express your brand and many options to build the ideal user experience that your users will appreciate.
Focus on usability as much as possible and make that the core foundation of your branding. That way your users will be much more forgiving of your early design flaws and bugs and that will give you an opportunity to earn the loyalty of your users over time.