It is time 有 4 个不同用法：
1) It is time + infinitive（动词不定式）:
It's time to start the race.(现在是时候开始比赛了.)
It is time to take a break.(现在是时候休息一会儿了.)
2) It is time + for + object + infinitive（宾语+ 动词不定式）:
It's time for us to start the journey.(现在是时候让我们开始旅程了.)
It's time for you to go.(你现在是时候去了.)
3) It is time + for + noun（名词为宾语）:
It's time for breakfast.(现在是时候吃早餐了.)
It's time for a break.(现在是时候休息一会儿了.)
4) It is time + subject + past subjunctive（过去式 - 虚拟句）:
It's time we went home.
It is time he came here.
It is time the police took action.
It's time you made up your mind.
上面第4类 (past subjunctive),我们用过去式动词 (simple past) 来说现在应该做却还没有做的事情,那过去式动词不是真正的过去式(虽然写法一样),这是带有假设意思的过去式,这个用法叫 unreal past 或是 past subjunctive.
句子
It's time we went home.是该回家的时候了
就是这种用法.
我是加拿大人,前英语老师.