testing = 1
TimeWhenCanRepeat = 0

$4::
{
	if (testing = 1 ) { ; Just as a test
		KeyWait, 4, T0.5
		if ErrorLevel { ; If you held it for <Default: 0.5> seconds, do..
			if (TimeWhenCanRepeat = 0) {
				DoThingAndSetTimer()
			}
			else if (A_TickCount >= TimeWhenCanRepeat) {
				DoThingAndSetTimer()
			}
		}
	}
}

DoThingAndSetTimer() {
	// Do thing
	TimeWhenCanRepeat := A_TickCount + 10000; current time + some time in the future, in ms
}