The three signals
One: the spreadsheet has a maintainer, and that person going on holiday is a business continuity conversation. Two: two departments hold different versions of the same number and both are defensible. Three: month-end is measured in weeks.
Any one of these is manageable. All three at once means the tooling has stopped keeping up with the organisation.
What Business Central replaces
Finance, sales, projects, inventory and manufacturing in one place, with the ledger as the single source rather than a downstream copy. For most SMEs the gain is that reporting becomes a refresh rather than a reconstruction.
It also connects to Dynamics 365 Sales, Power BI, Excel, Teams and Outlook. That matters more than the feature list, because it decides whether people use it.
The integration is the project
A Business Central implementation is rarely hard on its own. The work is in the integrations: synchronising accounts, contacts, opportunities, quotes and orders between CRM and ERP with mappings, business rules and transformations that hold under real data.
Build error handling from the start. Integration failures should log to Dataverse and appear in an app somebody can action, instead of failing silently until finance notices in the ledger.
When to wait
If your processes are still changing monthly, an ERP will encode a version of the business that is already out of date. Fix the process, then buy the system that enforces it.
We will tell you this at the health check if it applies. A go-live nobody was ready for is worse for us than a deal that lands a year later.