Definition (时间)
Used to indicate the moment when an action or event will begin or occur simultaneously, after counting to a specified number.
数到三（四，五等）的时候
On the count of three, I expect everyone to stand up.
数到三时，我希望每个人都站起来。
On the count of three, they tossed their grenades into the trench and fled.
数到三时，他们把手榴弹扔进战壕并逃离。
We’ll start at the same time. On the count of three – one, two, three, go!
我们会同时开始。数到三——一、二、三，开始！