Alexa alarm to create event

How do you set a timer to go off? In the rule:

rule "alarm Tracker" when
System started or alexa_Bedroom_nextAlarm changed then
 how to set the timer?
 timer goes off then vTimeOfday.postupdate("PREHEAT")
end

end then of course I have a seperate heating rule that tracks changes of time of day…
see DP - Heating Boilerplate - #7 by ysern