Alternative form of when it comes to (used for things in the past)

(business, stock market, chiefly northern US and Canada) Stock market securities can be expected to increase in value to a greater degree in the cold winter months from November through April than in the warm months from May through October, and profit-minded investors should manage their portfolios accordingly.

Alternative form of buy when it snows, sell when it goes

(usually in the past tense) To have known a famous person before he or she was famous.

Ellipsis of when the cat's away, the mice will play.

(idiomatic) Never.

(idiomatic) When the pressure is on; when the situation is urgent or critical

Unfortunate events occur in streaks or clusters, often in short periods of time.

(idiomatic) At a time in the distant past.

(idiomatic) At a time in the distant past.