If you mean add a delay before the response is sent, use a timer. See "/help /timer"

Example: .timer 1 3 msg $nick TESTING!
That is a timer that will wait for 3 seconds before sending the msg 1 time.
The period before 'timer' prevents mirc from displaying * Timer <X> activated and * Timer <X> halted
Code:
on *:text:test:?:.timer 1 3 msg $nick TESTING!