Conditional Shifting Cells to the Left Macros

The following is my last question for today:

In Row B I have a list of dates such as "Dec-31-2006", "Dec-31-2007", "Dec-31-2008","Dec-31-2009".
These dates begin in Cell B5.

I would like to create the following Macros:
If the function Right(B5,4) is less than 2008, delete B5:B21 by shifting cells to the left. Then I want the same condition to run again on the new B5 (from the cells that got shifted in), until there is a point where the function Right(B5,4)=>2008.

I want this Macros to run on all worksheets within my workbook. As a result there are some worksheets that might have an empty B5. I do not want these worksheets to have the macros run on them

Thank you so much for looking at my query.