Sorting by importance

Good morning!

I've created a drop down list using "Data Validation" for the column "TIME FRAME". I want the PRESET SORTING VALUE Column to add values automatically based on the information provided in the TIME FRAME.

PRESET SORTING VALUE----------------TIME FRAME
-----------8-------------------------------Fall 2013 (Sept - Dec)
-----------1-------------------------------Spring 2013 (April- June)
-----------6-------------------------------Meeting 2013-06-26
-----------8-------------------------------Fall 2013 (Sept - Dec)
-----------6-------------------------------Meeting 2013-06-26
-----------10------------------------------Meeting 2013-07-20

Can anyone help me?

USING EXCEL 2010