My little corn hatched a month later and is in a 12"x12"x12" exo terra terrarium. It would depend on his size, but most people wouldn't put a baby under 1 yr old into a proper viv. My Daughter's corn is 18 months, he's quite chunky and in a 3ft viv with a divider as it's still too big for him. Maybe go for a 3ft with a divider in it, save you having to buy something later when he grows, but you would need to block the sliding doors in case he escaped through the overlap
I've got mine in 2 foot vivs, I put the faun in there for a week or so and if they feed I put them in properly and if the feed again they seem happy enough. Make sure you've got lots and lots of hides and cover. 4 foot does seem rather big though :/
Frank (Amel Corn 1.0) Felicity (Flick) (Normal Het Albino BCI 0.1) Jack (Sunglow BCI 1.0) Maisie (Hypo het Albino BCI 0.1) Silver (Snow Corn 0.1)