asp calendar postback question

in my asp:calendar tag, I set the onselectionchanged to an event (date_selected) which gets fired whenever I make a new day selection. In order to tell the page_load about the selection change, I set a viewstate in date_selected to 1 and I check in page_load for the viewstate value of 1 to confirm the change. At one point in my application, it became necessary for me to know about the change of selection as soon as the page is loaded and not after the event is triggered. Is there a way to check in page_load if the onselection changed is raised? Or if any event has been raised for that matter? Thank you...