To add the print date and time to a report in Odoo using Odoo Studio, follow these steps:

1. Go to the Odoo Studio app and open the report that you want to add the print date and time to.
2. In the report editor, go to the "Structure" tab and click on the "Add an element" button.
3. In the "Add an element" window, select "Field" and then click on the "Create" button.
4. In the "Field" window, select the "Date and time" field type and then click on the "Create" button.
5. In the "Date and time" field configuration window, select the "Created on" date and time field from the "Field" drop-down menu.
6. Click on the "Save" button to save the changes to the report.
7. Preview the report to see the print date and time added to it.

Alternatively, you can also add the print date and time to a report by using the "QWeb" template editor in Odoo. To do this, follow these steps:

1. Go to the "Settings" menu and select "Technical" and then "Reports" from the sub-menu.
2. Find the report that you want to add the print date and time to and click on its "Edit" button.
3. In the report editor, go to the "QWeb" tab and click on the "Edit Source" button.
4. In the "QWeb" template editor, add the following code to the report template:

class="text-center">
  Print date and time: t-field="datetime.now()"/>

Click on the "Save" button to save the changes to the report template.

Preview the report to see the print date and time added to it.