differences - It's about time (vs) It's a matter of time

I would like to know if there is a difference in usage between these 2 structures.

In other words what situations might suit one and not the other?

• It's about time.



• It's a matter of time.

Answer

It is about time (about an event or action) is used when saying that it is past the time when something should have happened: it’s about time she got a job; it's about time you shaved.

About time

It is [only] a matter of time before (or until) something happens is used to express that something is sure to happen at some time in the future, but we are not sure exactly when. The house is burning, and it is only a matter of time before it collapses. If you keep swearing in the office, it is only a matter of time until you are dismissed. If you continue to torment the dog, it is only a matter of time before he bites you.

Only a matter of time