The schema is the product.
Model the domain before you write a component.
Ship UI fast, figure out the data shape later, refactor as you learn.
Every feature for the next two years fights the wrong shape. The 'small refactors' compound into a rewrite that nobody schedules.
Spend the first week drawing tables, foreign keys, and history columns. The schema you commit to defines the products you can ship and the products you can't. Treat it like the most important code you write — because it is.