This is the 1234th most frequent Japanese word.
タイミング
"タイミング" means "timing."
Here, the word "タイミング" is used to specify the time or instance when the event happened—his arrival.
彼が来たタイミングで電話が鳴った。
The phone rang at the timing he came.
In this sentence, "タイミング" refers to the synchronization of schedules or availability.
仕事のタイミングが合えば、一緒に旅行できますね。
If our work timing aligns, we can travel together.
Here, "タイミング" is used to emphasize the strategic choice of when to take action regarding the proposal.