You can start way before 12 with cooking. My son made scrambled eggs a day before his third birthday. (I just put the stuff out and told him what to do -- he put the butter in the pan, turned the stove on, cracked and scrambled the egg, and poured it into the pan. The only thing he struggled with was getting the egg out of the pan fast enough that it wouldn't burn, so I helped with that.)

In the kitchen he can peel garlic, fill ice trays, make bread dough into rolls ... and again, he's just turned three. He's much slower with all of those things than I am, but if I time things right, he's actually a (small) net positive. For example, he'll make one roll, and I'll make the other 7, or I'll give him 4 cloves of garlic 10 minutes before I need them.