The honest answer to "when should we hire a full-time CFO" is almost always later than the founder thinks, and earlier than the board thinks. Our rule of thumb: when the finance function needs a team, not a partner.
Three signals we look for: multi-entity consolidations with weekly reporting cadences, a capital structure that will require a CFO at the next round (cross-over investors, pre-IPO, multiple preferred classes), and enough transactional volume that your fractional spends more than half the engagement on execution rather than judgement.
We will tell you when we see the signals. Then we help run the search, write the spec, and onboard the hire. That hand-off is in the engagement letter.