A data stream, such as a video stream, may comprise one or more event trigger messages indicating an upcoming event in the stream. The time (e.g., pre-roll time) between the event trigger message and its corresponding event may be modified, based on rules, to provide a network operator, service provider or downstream recipient more (or less) time to prepare for the event. This may be accomplished by moving the event trigger to an earlier (or later) location in the stream, and/or editing the event trigger to indicate the different pre-roll time.