I started my sons out with tongue depressors, and a piece of sandpaper glued to a block of wood. I put tape on one end for a handle and had them sharpen the blade end on the sandpaper. I used the cub scout rules for handling a knife and enforced those rules strictly. I bought them a new Swiss Army knife, of their choice, and put it on a shelf so they could see it. The sooner they learned and could demonstrate the proper knife handling discipline, the sooner they could use their knife (under supervision). The knife handling rules were enforced whether they had a butter knife at the table, a saw cutting wood or a sharp knife.

They are very trustworthy now with any sharp utensil they use, and they enjoy their Swiss Army knife.