mmmmmdyyyy
Hmm... 5 m's returns the first letter of the month name... good to know.This will be as J for Jan, Jun & Jul, M for Mar & May. If that is not a matter you can also use a custom cell format.
Right Click >> Format Cell >> Custom;
Note: There are 5 m.Code:mmmmmdyyyy
A formula option is;
=TEXT(A1,"mmmmmdyyyy")