Oranges and other citrus fruits are highly allergic. It would not be good to offer juice at all at this stage, no matter whether he is formula or breastfed he is getting all of his daily nutrients. The absolute only time I fed DD juice was to ease constipation. And in that case it was diluted baby white grape juice. 1/2oz juice to 2 or 3 oz water. That did the trick. Now since introducing solids, I offer water during and after her meal. She actually really enjoys this, whether because it's in a sippy cup or because she likes the taste. She gets tons of vitamins A & C from her fruits and veggies, so there's no need to offer juice. I think the longer you wait before introducing, the better you'll be.