Of the three Schnauzer sizes, the Standard is the prototype, the miniature is the most popular of the three sizes, and the Giant,  not a giant breed, is simply the largest of the Schnauzers. What was the order in which the Schnauzer sizes were AKC recognized? Answer below image credit.

Miniature Schnauzer in oil by Debra Sisson
http://www.dailypainters.com/artists/artist_gallery/709/Debra-Sisson

The first of the Schnauzer sizes to be recognized was the standard in 1904. The Miniature Schnauzer came next in 1926, and the Giant brought up the rear flank in 1930.