Had better + bare infinitive is used to refer to the present or the future. We use it to give advice or to warn about something; to talk about some desirable actions that someone should perform in a certain situation.
I had better go now before it is too late.
You’d better start packing otherwise you’ll miss the train.
You’d better be quiet!
The negative form is had better + not + bare infinitive.
He’d better not take her earphones without permission - she‘ll get really mad.
I’d better not waste my time and go straight to the office.
The question form is made by moving ‘had’ to the beginning of a sentence.
Had we better leave a note for Tom that we’ll be out for the whole evening?
Hadn’t she better take the motion sickness pill? The waves are too big today.
It’s time + subject + verb in the Past Simple is used to express that the time has come for something to be done. It refers to the present moment and shows that the deadline is about to be reached, though there’s still some time left.
It is time the kids finished their breakfast. The school bus is arriving in a minute.
It’s time she started learning French.
It’s time (for somebody) to do something is a more delicate way to express that the time has come to do something.
It’s time (for us) to start tidying up the room, parents are coming home in half an hour.
It’s time to get going if we want to return before dawn.
We can add the word ’high’ to make this construction stronger. It’s usually used to criticize someone angrily for not doing something though it should have been done a long time ago. The structure is the following:
It’s high time + subject + verb in the past simple
It’s high time she returned the book. She borrowed it from me last year.
It’s high time you got a job. I’m not going to pay your bills anymore.
Another form of expressing that it’s already too late to do something, that it must be done urgently, and to show one's irritation because of it, is it’s about time.
It’s about time you came. I’ve been waiting for you for ages!
It’s about time the taxi arrived. We should be at the airport in twenty minutes.