Stop cell from updating when a date is reached

Good day,

I have two rows, one with the date of each Thursday of a course, the row beneath is linked to a cell in another excel sheet giving the percentage of the course currently completed.

When todays date advances past the date in the cell, I want the cell below to "freeze" and keep its current value at that time. As it currently stands, the past cells will continue to update to the current percentage completed and do not show the percentage completed at the time.

Any help would be appreciated.

Thanks,

Alex

bump?.............