Need some advice on building a platform that requires Facebook app

I have just recently begun working on my idea of a SAAS platform for helping online retailers get more out of their customers . This service is primarily going to be dependent on a Facebook app. I have always known Facebook's strict policies regarding app approvals. With no registered company in place, should i focus on building the platform first or should i first gather everything that is necessary for getting the app approved? If yes, for a solo guy what is it going to take to get an approval from Facebook for the app?