It's about time you sorted out your finances.

现在是你整顿财务状况的时候了。

《牛津词典》

It's about time teachers started to get tough with bullies.

现在教师该对横行霸道的学生开始采取严厉措施了。

《牛津词典》

He's a spoiled brat and it's about time he learned to behave properly.

他是个被宠坏的顽劣孩子，该是他学着行为得当的时候了。

《柯林斯英汉双解大词典》

He has brought needed supplies with him. "Wooo.It's about time you got back to earning an honest living.

VOA: special.2009.03.22

But I want you to take away from this how we reason about the complexity of these algorithms. And I'll remind you, we said we're going to mostly talk about time.

但是我想你们理解我们,是怎么推出这些问题的复杂度的,提醒大家，我说过了我们主要讨论时间问题。

麻省理工公开课 - 计算机科学及编程导论课程节选

And "it" definitely just refers to time and you only use "it" when you're talking about time.

这时，“it” 一词仅指时间，当你在谈论时间的时候，只能使用 “it”。

How long课堂 - SpeakingMax英语口语达人

There's another nice thing about time: It's the medium in which luck can occur.

FORBES: Magazine Article

Councillor Andrew Joyce said say it was about time something was done about the centre.

BBC: Rally against centre rebuild

"It's about time the moderates stood up and said, 'Hey, we're in the majority here!'"

CNN: STORY HIGHLIGHTS