Crossplatform mobile development pipeline

Please help me to understand how exactly I need to develop the project with must support three mobile platforms (Android, iOS, Windows Phone).

So for example I'm start development process and my first target will be Android. So I just switch to this platform and start development. Next I need iOS build I make a couple changes, add specific frameworks, etc... Next I do the same for Windows Phone. So I have three builds. Now I need to change something in the game add new futures ect.. Do I need to Switch back to Android and then to iOS and W Phone? Or I need to keep my development process for example in Desktop and do all changes there and after this copy project and change for specific platform. So my question is how exactly my development process need to be organized to let me switch platform as quickly as possible.