To set a Hidden until date:
Click Grades from the Navigation Menu.
Select Setup from the top row of tabs.
Click on the Edit option opposite the activity for which a Hidden until date is to be set.
Select Edit Settings.
On the edit grade item page, ensure that advanced settings are displayed. (Click the Show more button if not).
Enable the Lock after setting by unchecking the enable checkbox, then set a date.
Click the Save changes button.