The possible problem with that is that he will become "capable" at 3-4 months. As soon as your young does come into heat, he WILL breed them. Since they will be very (too) young/small, this could have some very bad results. I know you want the milk, so why not buy a proven doe in milk with a doe kid at her side? Many breeders have older does that are their final kidding. You'll have milk almost immediately through early next year. You can still breed her while you wait for your baby to mature for breeding & milk next year.