届时

届时 means 'at that time' or 'then,' and is used to indicate a specific point in the future when something will happen. It often appears in formal or written contexts, especially in announcements, instructions, or planning.

The character 届 (jiè) originally meant 'to arrive at a certain time' or 'to reach a limit,' while 时 (shí) means 'time.' Together, they emphasize a precise moment in time, often referring to a planned or scheduled event.

届时 is commonly used in official documents, schedules, and announcements. For example, it might appear in a notice about an event's start time or a deadline. It conveys a sense of formality and precision, making it less common in casual speech.