The antonyms for "kept waiting" can be "prompt," "on time," "punctual," "arrived early," or "swift." These words carry a positive connotation, and they refer to an action that is performed promptly and efficiently without wasting anyone's time. When things are prompt, they move quickly, efficiently, and without delay. On-time suggests that the event or meeting has started, finished, or arrived at the expected and planned time. Meanwhile, punctual means someone arriving or doing something at the precise time agreed, and arrived early simply means showing up before the appointed time. Swift means quick or prompt, which is perfect for situations that require the shortest time possible.