With F1 AOS would make much more sense. I'd suggest applying after the summer (taking 30-60-90 day rule into account). Is the Christmas travel really necessary? It's not unusual for people to sacrifice a vacation to get the bigger prize of a green card...if you have a low number you might even have your green card by Christmas, though doing AOS that is totally not a given the way it might be with Cp.
So is there no worry that if I only apply in September (which would be 60 days after my re-entering) this could negatively affect my chances of actually getting the green card? My CN is basically guaranteed to become current in October from looking at the past numbers. [To be clear: in this scenario I would do absolutely nothing until Sept, right? It's not like "submit one form but hold off on another one" or sth?]
(Also thanks so much for helping me out here, it really is appreciated!)