The most expensive financial mistakes in a practice are usually made at the very beginning, when everything is urgent and the numbers feel like something to sort out later. Later is when they are hardest to fix.
Start with structure. The entity you form and the way you set owner compensation are cheap to get right on day one and costly to unwind after two years of returns. Decide with your eventual income in mind, not just your first-year income.
Set up the books properly from the first transaction. A clean chart of accounts that separates categories the way benchmarks are measured means you can actually compare yourself to the 58 to 65 percent overhead range instead of guessing.
Plan overhead against a ramp, not a mature practice. Early collections lag production while referrals build, so cash is tighter than the schedule suggests. Budgeting as if you are at steady state is how new practices run short.
Build the monthly review habit immediately. Owners who look at collections, overhead, and cash every month from the start rarely develop the six-figure surprises that owners who wait a few years discover all at once.
None of this requires being a finance expert. It requires setting the structure once, correctly, and then watching a few numbers consistently.