example. 
sep 04
s   m   t   w   t   f   s
            1   2   3   4 - week 1
5   6   7   8   9  10  11 - week 2
12 13  14  15  16  17  18 - week 3
19 20  21  22 ....        - ...
oct 04
                    1   2 - week 1
3   4   5   6   7   8   9 - week 2
...