When you schedule the report, set that it depends on the event. When it is time for that schedule to run, it will sit waiting for the event’s file to appear which triggers the event and then it will run the report. Note that if the file was already there before the report’s scheduled time, it has to be deleted and recreated before the event will trigger and the report run.
Please read “File-based events” section of the “SAP BusinessObjects Enterprise CMC Help” for more information.