Custom Indicator Timer ??

[cochran1]

Does anyone know if an indicator can have a timer applied ?

I am working on an email alert that I will use for the London session but I only want it to activate at times around the session open (plus and minus ~1hr from the session open, say 1am to 3:30am). I dont want to wake up unless the trade opportunity is optimum. If so, do you know the code. thank you very much..