Keep feeding the Acan Dave and those babies will be full polyps in another month. After that, they will put out another ring around them. Once your one that second ring of babies, it's starting to look like a colony. Also, try to feed the baby polyps too. It's usually a little harder to feed the small polyps, but it helps them grow big and strong.
It really is amazing how quickly a single polyp frag can turn into a colony.