When using event based scheduling, reports aren't like buses 
Oemer Yazici wrote:
Of course i can schedule the reports every day but this is a overload. For a example if i schedule a report based on a event, every day this will generates a intance for everyday to wait for the event. Assuming that the event happens anytime monthly it can hold up to 30 intances for the the same report. And all this inctances will run when the event happens.
You're misunderstanding this; if the report is scheduled and that time passes without the event being triggered, the report will wait until the event is triggered (depending upon your scheduling settings). If this happens a week later, only one report will run - not 7. Instances are created by the event triggering the schedule - they don't accumulate and all run at once when the event is triggered.
In your example, if you schedule your report on a monthly basis and have it await a file based event, when the event is triggered the report will run; no instances are created for all of the days prior to the event occurring.
HTH
NMG