Okay, let's say you have an app idea. You have an idea person and an engineer to build it. You both have day jobs, you're going to start building this thing on the side as an MVP and try to get some traction with it before it becomes a full-time thing. You don't really need anyone else to get this job done except for some crowdsourced UI.
What other things would you do right away? Would you just build the app and see what happens? Any business-oriented things that you should focus on right off the bat, or can everything wait until you have a product in market?