I would like to write a formula that will do the following:

A B C D
1 Jan Feb Mar Apr
2 x x x
3 x x x x
4 x x
5 x

Looking for a formula to return the month of the first appearance of "x."
So "Feb" for row 2 "Jan" for row 3 "Mar" for row 4 and so on.

Any help is greatly appreciated.

Thanks