Here is the MDX query to reorder your Month

WITH

Member [OrderMonth] as

CASE [Month].Currentmember.Member_Caption

When 'Jan' THEN 1

when 'Feb' THEN 2

WHEN 'Mar' THEN 3

WHEN 'Apr' THEN 4

WHEN 'May' THEN 5

WHEN 'Jun' THEN 6

WHEN 'Jul' THEN 7

WHEN 'Aug' THEN 8

WHEN 'Sep' THEN 9

WHEN 'Oct' THEN 10

WHEN 'Nov' THEN 11

WHEN 'Dec' THEN 12

ELSE 'No Month'

END

SELECT

{(ORDER(([Month].ALLMEMBERS), [OrderMonth], ASC))} ON COLUMNS,

{[Row Data]} ON ROWS

FROM [DB Name]