Until a company gets to Product Market Fit (PMF), I’m a big fan of very small teams, two pizza or less. That gives you the maximum runway to find PMF and the most agility in switching directions as you discover your market.
For the subset of companies that do find PMF, then slamming on the gas of hiring is crucial. Otherwise, inevitably, there will be five Y Combinator companies with exactly your focus in the next batch and someone will beat you. It’s a very efficient market.
For many new f ounders, hiring is scary. You’ve never managed or led, many have never even hired another person. Now you are expected to match your growth rate with your hiring rate. That can be frightening if you are growing at 20% month over month. If you have 10 employees now, you will have 70 a year from now.
In a new company, I think of the first hundred hires as the most important cultural statement you can make about your company. Those people will replicate themselves many times over, often hiring people who act just like them, since we naturally bias towards people like us in hiring. So you can look at that first year as a Darwinian explosion, but you need to manage it as well as possible.