You can display the report run date and time on the report using a textbox and the Report Info button.

To display the report run date

Click inside the textbox as if to type in it. In the Report toolbar, the Report Info button is enabled.
Click the Report Info button. A list of report info values for the report drops down.

Select Execution Time. A purple box with an ampersand and ExecutionTime appears.

Tip: You can add more than one Report Info value in the same textbox, and add text around these values as is done automatically in Page n of m.