whens it time to think about a feature flag system?

hey all, ive been seeing feature flags pop up more and more, and they seem super useful for decoupling deployments from releases. but im curious about the tipping point. when does the complexity of managing flags start to outweigh the benefits? do you introduce them project-wide from day one, or only when you hit a certain team size or release cadence? what are your experiences with feature flagging frameworks or custom solutions