届时 (jiè shí): By that time / At the time (Adverb) — Meaning & Stroke Order

Are you sure you can arrive at the airport on time by then? The flight won't wait for anyone.

We plan to travel next month, and the weather should be nice at that time.

Although I really want to attend your wedding, I'm afraid I won't be able to get away to go by that time.

After the new policy officially takes effect, we will then adjust the plan based on the specific situation at that time.