How do i train my 4 month old green cheek not to bite?

I have a three month old nansun conure and this is what is working for me: When I can anticipate his biting, I keep a toy nearby as well as some treat seed. When he bites or nibbles, I slide his beak off and onto the toy. When he's done with the toy I tell him he's a good bird and give him a seed. Don't let him nibble as this tells him he's allowed to bite that object. Whatever you do, if he does bite, don't react...he'll try to bite agan to get that same reaction again.