The function schedule-timer-milliseconds schedules a timer to expire at a given time after the start of the program. The timer argument is a timer returned by make-timer or make-named-timer. The absolute-expiration-time argument is a non-negative real number of milliseconds since the start of the program at which the timer is to expire. If repeat-time is specified, it is a non-negative real number of milliseconds that specifies a repeat interval. Each time the timer expires, it is rescheduled to expire after this repeat interval.
If the timer is already scheduled to expire at the time this function is called, it is rescheduled to expire at the time specified by the absolute-expiration-time argument. If that argument is nil, the timer is not rescheduled, but the repeat interval is set to the interval specified by the repeat-time argument.
The function schedule-timer-relative-milliseconds schedules a timer to expire at a time relative to the call to that function.
schedule-timer-milliseconds has the same precision as schedule-timer, but may avoid some allocation when computing the time.
The following example schedules a timer to expire 15 minutes after the start of the program and every 5 minutes thereafter.
(setq timer
(mp:make-timer 'print 10 *standard-output*))
#<Time Event : PRINT>
(mp:schedule-timer-milliseconds timer 900000 300000)
#<Time Event : PRINT>
make-named-timer
make-timer
schedule-timer
schedule-timer-relative
schedule-timer-relative-milliseconds
timer-expired-p
timer-name
unschedule-timer
LispWorks User Guide and Reference Manual - 20 Sep 2017