When do children learn to snap their fingers?

Question

I am trying to prepare a developmental profile for pre-school children but I can't remember when that skill should develop.

Answer 1

 my 8 month old can do it 

Answer 2

 my 8 month old can do it 

Answer 3

 my 7 years old always used to move his fingers in different directions like put one finger on an other and use to  make birds aeroplane animals n so many other things plz guide me whats the problem with him.some time it looks very odd in gathering .