The word "un-timely" refers to something happening at an inappropriate or inconvenient time. Some antonyms for the word "un-timely" include "punctual", meaning happening at the appropriate time, "prompt", meaning done without delay, "timely", meaning happening at the right time, and "well-timed", meaning happening at a favorable or opportune moment. Other antonyms for "un-timely" might include "well-placed", "well-scheduled", or "well-oiled", all of which imply a sense of efficiency and organization. With these antonyms in mind, it becomes clear that one of the keys to success and productivity is being able to manage time effectively and balance competing demands.