I especially like march, april and july. Nice work!

I wanna make one of these

This is wonderful! I love it!

What's kind of ironic is that I actually have a MLP:FIM calendar, and the art is not this good. >>; I want your calndar.

I LOVE THEM ALL!!!
So I will save time and collectively comment here.
-JAN. = Amazing group shot, Love the outfits. The only thing I think is that you could have toned down the opacity on the glare on the eyes. since it is night time.
-FEB. = OH GOD, I AM THROWING MONEY AT MY SCREEN AS WE SPEAK. I absolutely LOVE Rarity!!!!! That is an amazing picture!
-MAR. = Oh man is that cute!! XD Such a nice Spring picture,
-APR. = Lol Gummy. I find it hilarious what you did there with the balloons.
-MAY = CMC! Yay~ I found this one quite hilarious that Cheerilee isn't really paying attention to them, just as they aren't paying much attention to her.
-JUNE = Princess Celestia! Bathing?! Avert your gaze!!! XD Great picture man,
-JULY = Sonic Rainboom... all the way... across the sky.
-AUG. = Silly AppleJack. Oh well, she's just doin' her job ^_^ Very nice work with that pose.
-SEP. = Oh Twi~ you book worm. It's just adorable!
-OCT. = So. Very. Great and Powerful. Love what you did there, cause I see what you did there. XD
-NOV. = MY BIRTH MONTH. I know it'll just as awesome as your other months pictures. You rock man! [Can't wait for these last 2 months. ^u^]