My son, who is 4 years old as of 23 of last month, has just started to go down the stairs by himself. (with one of us there just to make sure, and to give him encouragement if he needs it)
Before this, he would hold onto one of our hands to go down the stairs. He's been going up the stairs himself for a while now.
Also he used a spoon to eat his snack on his own, recently.
I'm very proud of him.