In rhetoric, kairos represents the fleeting moment when an argument or appeal will be most persuasive. In theology, it denotes moments when the divine breaks into human time. In archery, kairos was the moment when the target and circumstances aligned perfectly for the shot.
The concept recognizes that not all moments are equivalent. There are times to act and times to wait, moments of ripeness when conditions converge to make the previously impossible suddenly achievable. Wisdom involves recognizing these moments and having the courage to seize them.
Ancient Greeks personified Kairos as a young man with wings on his feet, hair in front but bald behind—symbolizing that opportunity must be grasped as it approaches, for once it passes, it cannot be caught. This imagery captures the fleeting nature of opportune moments and the importance of attentiveness and readiness.
Source
Ancient Greek Philosophy and Rhetoric