it is high time

It is the appropriate time (that something happen); it is long overdue (that something happen). Thank you for a lovely meal, but it's high time for us to start heading home. It is high time that someone gives him the punishment he deserves!

it's high time

Rur. it is about the right time for something. It's high time we were leaving. It's high time you started thinking about saving for your old age.

it is high time that

it is past the time when (something should have happened or been done).

it’s ˌhigh/aˌbout ˈtime (that)...

(spoken) used for saying that something should be done or happen immediately or very soon: It’s high time that this room was properly cleaned! ♢ So you’ve started work! It’s about time! (= you should have started a long time ago).