The signal to hire
Sales operations exists to remove friction from selling and to make the numbers trustworthy. In a small business, that work usually starts as a set of tasks distributed between the sales manager and whoever is most patient with spreadsheets. It becomes a role when the volume of it starts displacing the work those people are actually there to do.
Quantify it before making the case. Count the hours spent weekly on reporting, data cleanup, configuration and chasing people to update records. That number is nearly always higher than the estimate, and it converts a vague sense of needing help into a straightforward comparison.