你什么时候离开？

When will you leave?

What time will you leave?

When are you leaving?

Source: Tatoeba

Sentence Composition

=1 你 nǐ you (informal, as opposed to courteous 您 nín)
=1 你 nǐ you (Note: In Taiwan, 妳 is used to address females, but in mainland China, it is not commonly used. Instead, 你 is used to address both males and females.)
2 什么时候 shénmeshíhou when?; at what time?
3 离开 líkāi to depart; to leave