Popup message box upon running a report?

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Could someone please tell me whether it is possible (perhaps using custom scripts?) to present a dialog box when a user runs a report?

I'd want the message box to fire only between certain hours of a date (e.g. between 2017-01-20 1800hrs and 2017-01-21 0400hrs).

Better still would be a way to close the report once they have acknowledged the message box.

The background to this is that we have a report where users access a set of records relating to payments. During our accounting 'month-end', we have a weekend during which payments should not be approved (therefore we want to 'block' them from accessing the payments from this report).