I say no child is too young to be in the kitchen. Even babies. Yes, babies. If they can sit in a bouncy seat then can be in the kitchen helping. If they can sit in a bumbo, even better.
My kids have been helping me cook since they were teeny tiny. My oldest joined me on the counter in his bumbo and sucked on a wooden spoon. My twins had bouncy seats in the kitchen and listened to me tell them what I was doing. We’ve been in the kitchen since day one. And it’s paid off. My oldest is now making dinner from start to finish on his own – he’s 9. His little sisters are into baking and will whip out a loaf of bread by themselves, only asking me to help with ingredients and the oven.
When we trot through the grocery store, I tell them everything we are getting and what we’ll use it for. This does three things; it lets them know what they can expect for upcoming meals, it allows them to have some input about snacks and other more free flowing food, and it keeps me honest. I can’t drop a bag of peppermint patties in the cart without a good reason. They’ll call me on it and expect me to share them. Ha! That’s one thing that doesn’t get shared, they are all mine.
Start the life long habit of loving healthy food early by engaging them in the process early. Share what you are doing, why you are doing it, and what the outcome will be. You might be shocked at how much they retain and how happy they are to come back and help next time!