ahead of/behind time

ahead of time

Earlier than a given deadline. If we get to the theater ahead of time, we'll have our pick of good seats. My term paper isn't due until next week, but I finished it ahead of time.
See also: ahead, of, time

behind time

Later than expected, scheduled, or is appropriate. Go ahead and begin the meal without us, we're running a little behind time. We're sorry for being a little behind time with our takeoff, ladies and gentlemen. We should be departing shortly.
See also: behind, time
Farlex Dictionary of Idioms.

*ahead of one's time

Fig. having ideas or attitudes that are too advanced to be acceptable in the present. (*Typically: be ~; think ~.) Sue's grandmother was ahead of her time in wanting to study medicine.
See also: ahead, of, time

*ahead of time

beforehand; before the announced time. (*Typically: arrive ~; get there ~; leave ~; show up ~.) If you show up ahead of time, you will have to wait. Be there ahead of time if you want to get a good seat.
See also: ahead, of, time
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

ahead of time

Earlier, sooner, as in The meeting was scheduled for three o'clock, but most people arrived ahead of time. [Early 1900s]
See also: ahead, of, time

behind time

see under behind in.
See also: behind, time
The American Heritage® Dictionary of Idioms by Christine Ammer.

ahead of/behind ˈtime

early/late: He arrived ahead of time, and had to wait. The trains are running behind time again today.
See also: ahead, behind, of, time
Farlex Partner Idioms Dictionary
See also:
  • arrive
  • ahead of the game
  • in good time
  • ahead of schedule
  • schedule
  • in time (with someone or something)
  • not about to
  • not be about to do something
  • front of house
  • nick of time, (just) in the