If you had more time i'd say do some research on agile/scrum but heres a cut down version:
1) Initially you want to sit down together and very carefully plan out your application and all of its features. You also want to sketch out(wireframe) the user interfaces remember that their are a huge variety screen sizes, try and keep them minimalist.
Remember features are for the benefit of the end user, always remember if someone wants to add something, ask what the benefit is!
2) You absolutely should have more than one meeting a week, you should be meeting every day even if for only 15 minutes either face to face or on skype. The reason being you can discuss problems, find solutions together and most importantly adjust timescales and resources accordingly
3) You should then assign priority to each of these features along with the amount of time it will take you as a team, we use the MoSCoW scale for prioritization. You should then see if your specification can be feasibly finished in the time required, if it doesn't you may need to either redesign some features or drop low priority ones.
4) Start working as a team on the high priority items working your way down the list.
5) As you complete each item you need to go back to you original specification and check you've actually achieved the goal.
I can't stress enough how important you're daily conversations are, don't ever let anyone not attend unless they are on their death bed! If you're going to manage the project you need to know about issues very quickly.