Develop a comprehensive project plan, a map of the work you will undertake for the rest of the semester. You've had some time to sit with your original concept. Your ideas have evolved while developing project-specific deliverables, a lightweight prototype, and a preliminary user study. Use this basis to forge a plan!
A key aspect of the project plan is scope. Be ambitious and realistic at the same time. Push yourself, but make sure you are building something that while enable you to build a truly functional prototype. You will run a user study with this prototype. The study must be meaningful. This means, for example, that you cannot build a game or social network project that requires many participants. Scope your project to the scale of the resources that you have.
The project plan template can be found here.