とき can be used to say when you want somebody to do something
銀行へ来るとき、カードを持って来てください。
When you come to the bank, Please bring your card.
It can be used with adjectives
眠いときは早く寝ましょう。
When we’re tired, let’s go to bed early.
As well as present-tense verbs, adjectives and nouns, とき can also be modified by past-tense verbs.
リポートができたとき、教えて下さい。
When the report is ready, please let me know.