As Barbara does not normally visit the forum, let me try to answer this.
The target for mailing the bulletin is the 30th of the month before or the closest post office day to that. Barbara and I do all the labeling and attaching of stamps (the printer gets it to us folded and tab sealed). We mail from the Rocky River, Ohio Post Office. To make this, we have a cut-off date for material of the 15th, to allow time for printing. As we both have day jobs the label/stamp part typically is done over a weekend and the material goes to the P.O. either Saturday afternoon or the following Monday afternoon. There could be a slight change in the flow from month to month but target for mailing is the 30th of the month before.
Quarterly, Roster and Calendar are done by someone else who has their own printer and mailing activities. For info here, contact Mike Barker; he is responsible for it.