I need date inserted in google docs when checkbox is selected

Hi, I need designer who specialises in Google Docs. I'm designing a basic sheet for my school to track student payments for events. When someone pays and a check box is selected, I need it to put the date in the adjacent cell that the checkbox was selected. This is so we know what date someone paid.
In this sheet, when someone ticks the "$70 Bulk" Checkbox, I need the date that the checkbox is checked to appear next to it in the receipted column.