The artist releases new pictures every so often, so I'll keep this updated [within the rules]. Also, English date system because not American.
Files are in alphabetical order. Updated with the artists latest image, "Princess Twilight Sparkle" [image 40 in the gallery].
Seems the artist is going to be using the same file names from time to time, because images 21/22 are both called "Fluttershy", and 42/43 are both called "Rainbow Dash". In the case of files having the same names, the newest one is second.