Your corn will look small Tina, especially when compared to the pinkie he is expected to eat. Have a look through the photo section and video section...there will be feeding pics/vids that give you some idea of what to expect. You can checkout Kellog's video...I know he is an adult, but when he first fed on a jumbo mouse it looked way too big to go down.
Remember that you are in the one-week settling in period, with no handling or feeding, so you have time to checkout your concerns.
he'll be fine if you are worried ask your rep shop to give you the smallest pinkies they have, most rep shops will be happy to do so look forwards to the pics but like Kellog said - dont forget to leave him for a week!
2.0 Normal Royal Pythons - Q and Little One 1.0 Chihauhaun Mountain Kingsnake - Simba