Uhhhh, well, the default settings for IIS is to shutdown the website after a certain period of inactivity. You will need to start by turning that off I believe.
Also, there never seems to be a really active process happening, although you might be able to do something in the application startup section.
After you figure a way to keep something running at all times, it should be a simple task to decide if the date/time combination is correct and then fire off the event to email out what you want.