The antonyms for the word "well-timed" are poorly timed, untimely, ill-timed, mistimed, and inappropriate. Poorly timed refers to the act of doing something at a time that is inconvenient or disadvantageous. Untimely implies that something happened unexpectedly or inopportunely. Ill-timed implies that an event is challenging or embarrassing because it happens at a wrong time. Mistimed is when someone fails to do something at the right time. Inappropriate refers to something that is not fitting or suitable for a particular situation. Overall, these antonyms indicate timing that is lacking in suitability, appropriateness, or convenience.