Last on our list, but not in your process is development collaboration. The earlier in your process that you begin working with your developers, the smoother the handoff can be. In fact we should even avoid having a ‘handoff’.
While some developers will be keen to collaborate and share their knowledge. The best developers will enjoy the conversation, and the challenge of pushing the platform. As you iterating your design, validate on device and with real customers, the developers should be involved. Showing your early prototype will allow the developers to give crucial feedback, but also enable the design to iterate based on what’s possible on the device.
Your prototype is also both a proof of concept and your documentation.