You are right on the money here. Comics always had arrival dates from between 2-3 months from the cover date. The cover date actually is the date that a book was to be removed from sale to make room for the newer books and to get credit for unsold copies. The Edgar Church copies (for example) are very interesting because of the arrival dates in addition to how many copies were ordered.
You really noticed this in England, because over here, newsagents always sold in the cover month. Consequently, when buying new issues in the 70's/80's, you had a choice of going to the nearest shop and picking up FF175 or going to a mart and getting FF176, 177 and 178 (for about two to three times the price).
I'm not familiar with new stuff either, but didn't they harmonise the dates to the real calendar about 10 years ago ? If so, how did they do that, did they just go October, October, October until they caught up ?