It’s time to do… it’s time to did … it’s about time you did … SOMETHING.
It’s time to + PRESENT TENSE: it’s time to do, it’s time to go: …
When you want to tell somebody to do something…
It’s time to leave … it’s time to go …
It’s time to left … it’s time to went …
It’s time to + PAST TENSE: it’s time to did, it’s time to went: …
We use the past tense, but with a present meaning!
Examples:
Children, it’s time you DO your homework!
With a present tense: you should start your schoolwork.
After, you can watch TV.
Children, it’s time you DID your homework!
With a past tense here (did): you should have started it.
You should have done it! If not, you can’t watch TV.
It’s ABOUT time you + PAST TENSE: it’s about time you did something …
with about, it gives a stronger force.
It’s about time you wrote the letter (and not just talking about it).