PREDICTIONS:
May - Aurora (with the fairies [or just one of them]) (Maleficent comes out on the 30th, so it seems like Disney would have this one release this month so the pins could go hand in hand)
June - Cinderella (with Jaq or Gus) ("Cinderella" always seemed to have a spring/summer feel in the movie in my opinion. Since the transition between these seasons takes place during June, I think Cinderella will be the calendar)
July - Ariel (with Flounder) (July is one of the hottest months, and Ariel seems like she is a summer princess for sure)
August - Snow White (with Dopey) (She just kinda fit here after process of elimination :lol
September - Belle (with Lumiere) (For some reason I always associate the month of September with the color yellow, and Belle wears a yellow dress. Also, Lumiere is a gold yellow color and he might be showcased on the front of the calendar. Furthermore, Belle seems like she wouldn't fit if she was put in any of the later month's calendars in my opinion)
October - Merida (with a bear cub) ("Brave" seems like it took place in the fall, so I feel like Merida will be either October or November. I think Pocahontas fits better for November than Merida does, so I think Merida will be on the October calendar instead)
November - Pocahontas (with Meeko) (Clearly, "Pocahontas" takes place some time in the fall. Since, Ratcliffe (the villain from Pocahontas) was the November calendar for the Villains calendar set, I think Pocahontas will be the face of the November calendar for the Princess Calendar set)
December - Anna [possibly with Elsa as well] (with Olaf) (OBVIOUS REASONS)