It depends........
How old is the snake ??
Better yet, What is the size of the snake at it widest point (what the girth?).
A general rule is that you feed a corn snake an food item that is no greater than 1 1/2 times the snakes girth. And when feeding the snake a pinky does it leave a noticeable lump in the snake after eatting??? How long have you been feeding it pinkys??? So more information is needed to give you a answer.