The trigger is rarely revenue. It's the moment financial decisions start outpacing financial information.
The usual signal is not size. It is decision density: pricing, hiring, financing and expansion questions arriving faster than the finance function can answer them.
A fractional model works when the company needs judgment more hours than it needs a full-time salary — and when someone senior is also willing to build what is missing.
Scope it around outcomes: a reliable close, a forecast leadership trusts, and a monthly decision agenda. Those three make the rest of finance easier to fix.