I haven't looked at Arnel's suggestion, but I would first choose which format you wish to use for all dates (mm/dd/yyyy or dd/mm/yyyy). Perhaps, he does this in his example.
Then, in columns D and E I would create a formula that formats the unambiguous dates in your format of choice, and writes 'CHECK' for the ambiguous dates so that you can verify them manually.
the Column SSINIT is Text, using CDate() will convert it to date (in your Locale), so you don't
worry whether the first number in the text is a Day or a Month.
Your Locale will determine that using CDate().