Long past the right time; also, approximately the right time. Thus, It's about time you went to bed can mean either that you should have gone to bed much earlier (often stated with emphasis on the word time), or that now is the appropriate time for you to retire. [Early 1900s] For a synonym, see high time.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.