I think I see where you are going. Let's try this.
Assume the word "Available" is in cell B2. Move it to B1 and put the
date 12/7 in B2. In cell B3 enter the formula,

index(E3:H3,1,MATCH($B$2, $E$2:$H$2))

Copy this formula down and you should be good to go.

- John