What is the biggest mistake non-technical founders make?
Not getting the code into version control early. Without it there is no history to recover from, no way to see what a change did, and no clean handover to a developer later. It costs an hour on day one and is very expensive to retrofit.
From How to build an app without code: an honest guide, published 9 August 2026. That article is where the reasoning behind this answer is set out, including what it does not cover.