I think the rule of lower case # will get their visa first doesn't apply for AP cases because they cannot hold on a visa slots due to uncertainty. So I believe once a case # become AP it no longer follows the rule of lower case # take the visa slot first instead they will go by whichever AP cases get clear first will get the visa slot even the one get cleared has a higher case #.
DOS somehow made FBI process AP cases by the end of year end - almost instantly. If DOS wants FBI to process them earlier, I do not see any major factor preventing DOS from influencing FBI earlier than the end of fiscal year. In DV-13 they did not need it earlier, but in case they need it earlier, what is the problem to have it earlier?