Miss Mega is 1 year 2 months old
Zilla is 4 years 0 months old
With kids you could say: "If you build it they will do."
If you make a way for the kids to reach the sink, if you have aprons, sponges and a water faucet within reach, the kids will be free to do what they want to do.
At 1 year old a walking toddler can carry her dishes to the sink. By 18 months she can do a basic wash/rinse. From 2 years old on the ability to wash the dishes properly continues to increase.
When we have our morning snack Zilla and Mega are in charge of washing the dishes. Ok, Zilla does the watching and Mega gives him admiring looks and encourages him with giggles. At meal times the kids help set and clear the table but due to the small size of our kitchen the washing up is limited to one adult.