The best thing to do would be to confine the kitten to one room for the first week or so. That way you can make sure he knows where his litter box is and you won't have to hunt all over the house for him when he goes missing.
Could you put some net over the gaps so he can't squeeze through?
I'd recommend getting him used to a harness so that you can take him for walks around the block. That way if he ever does get out he will know where he is and won't panic and run away.