Theres no way you can order something which has no sortable field (property) unless you hardcode the order.
You must have an attribute in your time (month) dimension which is sortable.
From the code you pasted you cannot see it.
In our cubes sorting is coded within the cubes using say, month ID, year, day etc. so that we do not have to sort it outside of the cubes.
M.Sc.IT, M.B.A, MCTS BI 2008, MCITP BI 2008, MCTS SQL Dev, CSM, CDVDM