Here is a recommend prey weight to corn snake weight ratio that I got from another forum I'm on. Hope this helps.

Pinkie 2-3g every 4-5 days 4-15g snake
2 pinkies 3gx2 4-5 days 16-23g snake
small fuzzy 5-7g 5-6 days 24-30g snake
fuzzy 7-9g 5-6 days 30-50g snake
hopper 9-12g 5-6 days 51-90g snake
weaned mouse 14-20g 7 days 91-179g snake
adult mouse 24-30g 7 days 170+ snake

good luck.