I think it's about the MVP - minimum viable product of the company. The first product which is going to bring in revenue and keep the lights on. You will obviously consolidate further and build a business plan around the MVP. Basic for Altair was Microsoft's MVP. Offering air mattresses was AirBNB's MVP.
Looking at Wikipedia, it appears they spent several months before launching their site, after getting a technical cofounder. So 3 people and 6 months, at least. I find it very hard to believe they did all that with the idea their MVP was renting out their flat.
