Kids soccer cleats are so important as soon as the child is ready to wear them.
Sometimes it takes a year or two before the younger player are ready to wear them practices.
Encourage them, don’t force them. Usually by U8 they are ready if not sooner.
Remember, socks play a big roll in wearing cleats, most kids wear thicker socks for games.
Diadora Furia MD Junior Soccer Cleats at under $20 per pair are good cleats to try.
See the link for Soccer Garage below for very good pricing on this shoe.