Your comments

Hi Michael and thanks for that quick reply.

I must be reading the lists wrong.

I'm looking at the Rosh Chodesh lists.

In the column for 2015/2016 (5776) the last entry is Rosh Chodesh Elul September 3rd. Then, in the next column 2016/2017 (5777) the first entry is November 1 (Rosh Chodesh Cheshvan). So I calculated (obviously wrongly) that Elul contains most of September and all of October.

Have you done a calendar (like in a google calendar, or the typical month by month wall calendars) with the first days of each month ?

Thanks in advance

MarT