Can you explain the use case a little more please?
It sounds like you have a file event which may take place from the 5th to the 15th of the month. This being so is there an existing workflow which requires the event to progress or should this event trigger a new workflow?
If this is the case then a suitably configured file event seems like the way to go.
It sounds like the simplest way to accomplish this would be to create a custom calendar that includes the days from the 5th through the 15th of each month. Point your existing job to that calendar and if I understand the scenario, that should do what you want.