One of my field data is like below
I am excepting o/p is like this in Dimension level(UI Level only need)
You should use the function "month(Month)" and set the variable in the beginning of the script before the load like this :
add as dimension:
Question not clear, You could create one more field with full names and use the same where you want?
Pick() function is the right way but you can try with if also or may be in the script level also.
By Calculated Dimension