Typically, how far in advance of the cover date did the railways supply data to the ORER publisher in the era when the ORER was issued quarterly?

Specifically, I am looking at the WP's first group of Compartmentizer-equipped PS-1s, delivered in 11-51 in series 20801 - 20820 in the all-silver with large orange feather scheme and subsequently re-numbered into series 19501 - 19520 in the same scheme. The January 1953 ORER shows 14 cars in the new series and 5 remaining in the original series (one has apparently disappeared). Series 19501 - 19520 is indicated as a new addition (presumably since the October 1952 edition) but the 20801 - 20820 series is not indicated as a reduction in the number of cars since the previous edition.

For my mid-September 1952 layout, I am trying to determine which series would likely be the predominant one. Does anyone have an October 1952 ORER who would be able to check whether series 19501 - 19520 is shown in that edition?

Thanks for any assistance.

Greg Kennelly
Burnaby, BC