Below is taken from David Sacks blog post about sales compensation:
Three rules:
to keep incentives clean and predictable.
With those ratios, a rep’s fully-loaded cost stays near 25 % of new ARR, which—paired with spending up to 50 % of new ARR on marketing—keeps CAC payback comfortably under 12 months, the efficiency hurdle most venture investors expect before you scale.
Start with two AEs; when ≥ ⅔ consistently clear ~80 % of quota, layer in a manager (whose team quota should be ~-20 % lower) and add more reps—if they’re missing, fix price or pipeline first

*On-Target Earnings