You have a create date in Datetime format (ugly!). You want to create a nice row label of out that for your SSRS report. Well here ya go!:

Set the text box to an expression:

=MonthName(Month(Fields!CreateDate.Value))&" "& Year(Fields!CreateDate.Value)

This will give you a nice date label like “December 2015”.

For an even snazzier label, I like:
=Left(MonthName(Month(Fields!CreateDate.Value)),3) & "-" & Right(Year(Fields!CreateDate.Value),2)

This gives you a label like this:

Dec-15