It's wrong to say "It's time we go". But can we say "It's time we should go"?

A friend of mine told me that it should be "It's time we went." But he doesn't know why we should use 'went' when we haven't left the place. Could someone tell me whether there is a reason for the usage?
It's time that we should go.
it's normal to me, derived from
It's required that we should go.
(should go is necessary after required that)

Then "should go" can be replaced by "went" as another subjunctive substitute and we're at:
It's time we went.

Basically we're dealing with expressions for a requirement.

There are often several ways to say the same thing Emotion: smile
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The expression It's time ... usually takes a past form even though the meaning of the clause which follows is timeless / hypothetical.

It's time we went.

The usage is the same as in this if-clause: If we went now, it would be the right time.

The base form is often substituted.

It's time we go.

And the FOR ... TO ... construction is also frequently and correctly used.

It's time for us to go.

 Marius Hancu's reply was promoted to an answer.

All along, I thought it was wrong to say "It's time we should go". I always thought that it should always be "It's time we left."

However, I've seen it written "It's time to go". It is also what CJ has written in his reply.

Thanks for telling me that the sentence is correct.
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 nona the brit's reply was promoted to an answer.