a good opportunity has come; the time is ripe
A yojijukugo (four-character idiom) meaning that the right moment for action has arrived. Often used in formal or literary contexts.
The time is ripe for reform.
He was waiting for the right opportunity to come.
A yojijukugo composed of 時機 (opportunity, right time) and 到来 (arrival, coming). The exact historical origin is uncertain, but it follows a common pattern of classical Chinese-derived four-character idioms.