Rule

The implied daily move (shown on every simulated candidate) is what IV charges per day. Compare it against the underlying's RECENT REALISED daily range.

When it applies

Before selling any premium, and before buying any.

What it means

Implied above realised: short premium is being paid for. Implied below realised: you are donating. This is the single edge test that matters for a short-dated book, and it replaces reasoning from IV level or IV rank, which say nothing about whether IV exceeds FUTURE realised vol.

Caveat

The number is the same for every structure at one spot and one flat IV - it is a property of the underlying, not of the trade. It varies between structures only through skew.