I have the following sentence.

> 
> Notify the persons before 30 days
> 
> 
> 

How can I create a question for this sentence?

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> Before how many days the persons should be notified?
> 
> 
> 

Am I correct?

To make the question clearer: Suppose the Identity Card of a person is going to expire next month. The system needs to inform the person before 30 days. Does the word *within* match my requirement?