We use this expression to say that we think someone should have done something before, or something should have happened before. It’s common when people are late.
You can use this phrase in ………… language.
A: Here’s Honza – he’s coming around the corner now.
B: About time. I’ve been waiting for 30 minutes.
A: They’ve finally fixed the lights by the river.
B: About time! It’s been like that for months.