Whenever you create rules, you will have to have an Event that triggers the rule.  The three standard events a Form can raise are when it's Initializing, Initialized, or In Error.  Initializing refers to during the Form's rendering process.  Initialized is the first step after the Form's rendering process.  In Error will fire off if the Form reaches an error state.  

You can find more about the Events that can take place on both Form and View levels by following this link: 

http://help.k2.com/HelpPages/K2smartformsUserGuide1.0.7/default.htm#SF_-_Rule_Designer_-_Events.html%3FTocPath%3DK2%20Designer%7CRules%7C_____2