Signals: FOMC, CPI, NFP, earnings, or any event that changes the informational backdrop. Wide candles, fast moves, and abnormal volume in the first 30 minutes.
Behaviour: Volume will often build a new area of acceptance only after the first impulse — not during it. Early structure is unreliable.
Your approach: Treat early structure as provisional. Wait for the impulse to complete and a new acceptance zone to begin building before trading the profile. Reduce size proportionally.