My son, who's a bit over 7 months old as of this writing, is a delicious babbler. He's had the bilabial sounds pretty much together for quite some time—"ba ba ba ma ma ma"—but has only recently begun the alveolar plosives—"ta ta ta da da da".
I know that he's babbling; I know that he's not naming anything. But whenever he goes "da da" I just melt.