Are you a geek too or are you the business person?
Advice #1: Be wary of what you read on these boards. A lot of folks will tell you that you need to do "x". Well, what they aren't telling is that they think "x" will work for you but what do they really know about your idea? Zilch. "x" might have worked for them or for a friend and now they pass it along to you. They are trying to be helpful yet that doesn't mean they are helpful. Be wary.
Advice #2 - Decide whether you and your friend actually want to be the implementers or you want to sell the idea for someone else to implement.
Advice #3 - Consider talking to a patent attorney if it is an interesting enough model.
Finally, the process to go from idea to product varies too widely for me to offer specific advice. If your friend can code it in 6-12 months, here's what you have to consider:
* If it can be coded in such a short period of time, how quickly can it be copied?
* If he can code it by himself in 6-12 months, how realistic are his timelines? It's often that I find my project estimates to be wildly optimistic...
* If he can code it by himself in 6-12 months, how much faster could he do it with a team of four other people who are very talented working alongside him 60 hours a week?
* Assuming that a team of 5 can code it inside of 90 days, is there an opportunity cost lost by waiting the extra 90 days (for your friend to code it alone)?
* How long will it take to raise financing (to fund the 5 person team)?
etc
Good luck!