When I played, I don’t recall any checking age limit. Personally, I think hockey went the wrong direction by moving the checking age to Bantam rather than down to Mites.
Bantam has a huge spread of physical maturity between the boys, with large weight and height differences. Coupled with not learning to keep heads up because of no checking at younger age, it’s a recipe for head and body injuries.
Let them learn about checking when they’re all small and light of weight, and learn to keep their heads up. The collisions are nonviolent in comparison with older age groups.