Calculating Turn Around Time by date

You could probably make it simpler by making column A into dates (however displayed) but my solution supposes that you change nothing except add the year to cell A1 only.

If you don't specify the year then it will assume the current year, so that might be OK now but as soon as you get to 1st jan 2013 it will assume 2013. If you want to control the year change yourself then better to put in in A1 (or use any other cell but change the A1 in the formula)