Add a second field to your table of type date. You'll want it to be of type date so that the dates sort correctly.
Do a show all records, put the cursor in the new date field and use Replace field contents to convert the text to an actual date in your table:
Replace Field Contents [YourDateField ; Date ( Middle ( YourTextField ; 6 ;2 ) ; Middle ( YourTextField ; 9 ;2 ) ; Left ( YourTextField ; 4 ) ) ]
"YourTextFIeld" is what I am calling your current field with the imported date.
Note that dates are stored internally as a number when entered into a field of type date. You can use data formatting in the Inspector to specify any date format that you need for display on your layouts.
That helped me a lot!
Many thanks and sorry for my late answer!