I really didn't have any infusoria - whatever was around when they were born. I didn't add any.
After their egg sacs have gone away (usually a couple days after hatching) they can start to eat. I started them on the worms listed, and BBS here and there as well. So far no issues eating, etc. As long as the food moves and is small enough, they should be fine. Infusoria isn't a must.. it helps, and is good for them, but I just couldn't get enough to make it worthwhile so I just tossed in my plants when I set up the tank and let it do it's own thing - and started feeding them when I saw some egg sacs depleted.
Breeder so I have too many to count and too many named to list here!