8 Day old Cockatiel..HELP

[Prettywings]

Hello, Just wondering at what age are the cockatiel chicks too big for the parents to sit on? my chick is 8 days old, the parents are feeding him constantly but they are not always sitting on him...just wondering if maybe he is just too big sit on?? I do notice that he always gets away from the nest (on the bottom of the cage). I noticed that he is pretty mobile..he uses his legs and pulls himself around on his bum...his eyes arnt open yet so he cant see where he is going!

Just looking for some advice!