once upon a time

:  one time and no more

:  at any one time :  under any circumstances :  ever

:  at some indefinite time in the past :  formerly

:  one single time :  one time at least

:  that once was :  former

:  at the moment when :  as soon as

:  on

:  on the surface :  on it

:  thereafter, thereon

:  the measured or measurable period during which an action, process, or condition exists or continues :  duration

:  a nonspatial continuum that is measured in terms of events which succeed one another from past through present to future

:  leisure

:  to arrange or set the time of :  schedule

:  to regulate (a watch) to keep correct time

:  to set the tempo, speed, or duration of

:  of or relating to time

:  recording time

:  timed to ignite or explode at a specific moment