You need a CRM the moment the flow of leads and customers becomes something you cannot track in your head or in a spreadsheet. The classic warning signs are concrete: you are losing contacts, you forget to follow up on quotes, or more than one person handles customer information and nobody knows who owns a lead.
It is a common misconception that CRM software is expensive and complicated. For a small business the starting point is a simple tool with a free or low-cost tier: a contact list, follow-up reminders, and a note of where every deal stands. Most teams only ever use a small fraction of the features a big platform offers, so buying an enterprise suite from day one is wasted money.
The other trigger is process, not technology. If your team has no defined way to handle an inquiry from first contact to sale, a CRM will not fix it. Put the simple process on paper first, then let the tool enforce it. That is the order that works.
If you are already losing leads or missing follow-ups, the cost of not having a CRM is higher than the price of one. Start small, move in, and add automation and reporting only when the basics are running smoothly.