From watching a lot of people go through this, the three mistakes arrive in a predictable order and none of them is buying one too early.
Wearing it for everything. Warm-ups are where bracing gets practised, and a belt on a warm-up set removes the practice while giving you nothing back. Belt the sets that are actually hard.
Cinching it so tight you cannot breathe into it. People assume tighter equals more support and it inverts the mechanism — you need room to expand into it. Tight enough that you notice it strongly when you brace, loose enough that a full belly breath still happens.
Treating it as permission. This is the one that actually causes trouble. A belt makes a heavier weight feel more manageable, so the temptation is to add load faster than your positions can hold. The rounding you were fighting at 90 arrives again at 110, and now there is more weight on it. Progress at the same rate you were, and let the belt improve the quality of the reps rather than the size of the jumps.
One thing worth adding: it is a training tool, not a medical device, and it does not make an unsafe position safe. If something in your back is complaining, that is a conversation for somebody who can actually look at you, not a purchase.