In our brooder, we teach them all to drink from the waterers, each one, all 90. But there's always one, in every flock that pecks the floor (that has food spread on it, on plain paper) and discovers food. Soon they are all pecking away. So we've never had to worry about teaching them food.
Once they have found the food on the floor, they inevitably find what's in the feeders, usually within 2 days. At that point we put bedding down (it's really needed by then) and put the feeders around the brooder and enclosure.
This year we have heaters and will not use the brooder. So we'll be figuring out a slightly different method.