Well, there isn't too much you can do to speed it along, it really just needs time. I would recommend reading that article I linked to in my last post if you haven't already. The only thing to make it go faster is to ask a friend who keeps newts or fish to give you a piece of driftwood or a rock out of their tank and to put it in your tank. You have to make sure to transport it in tank water to keep the nitrifying bacteria alive! It works best if you add the article from the friends tank at the same time as the axolotls.
Regardless, with that many axolotls make sure to watch your aquarium parameters closely the first month you have your axolotls and be prepared to do plenty of water changes.