My -guess- isn't 100% accurate, probably, since I don't personally own corns. If I were to guess I'd say maybe 8 - 12 months? As I said, it's probably wrong and I'm just guessing.
I'm glad Scott put the 'birth date' on the lid of my snake's little container he was sold in

October 9th~
Edit: Ahhh that's very true Rob. Shame on me for forgetting eating and all that jazz. For the record, I was basing my guess on a corn fed the appropriate sizing and fed once every 6 - 7 days, and also with adequate husbandry.