Business models, how ever rudimentary matters early on today. Pre-revenue startups and their valuations are not what they were 10 years ago.
Your early business model's trigger function should solely rely on Gross Margins (GM).
Know your fixed costs vs. variable costs and how to differentiate them. http://bit.ly/2x59el4
Use technology to reduce / negate fixed costs and make variables directly correlated to KPIs.
Understand your vertical's revenue / employee averages - https://read.bi/2x8z1c4
Understand your CAC, LTVs and how marketing / growth spends effects those. - http://bit.ly/2x5bqci
It's perfectly ok if your business model starts with 1 paying customer and evolves during the first few years.