Checkbox Report

How are your users checking the box? In order to track what you're looking for - you'll need to add in some functionality to log when the actual box is checked. 

If you're users are checking the box from a native Quickbase form - a simple form rule will do. First you'll need to add (2) fields - 'Checked By' (user field) and 'Check Date/Time' (date/time) field. 

In your form rules - you will make a form rule that says when checkbox is checked - populate 'Checked By' with the current user, and populate 'Checked Date/Time' with the current date/time. Then you can add those 2 fields to any report you need them on.