It doesn't matter if your child doesn't walk by the time he is one.
Or is not toilet trained by two.
Or doesn't use cutlery properly at age three.
Or doesn't write his full name when he is four.
Or tie shoe laces when he is five.
Or master a school tie by the time he is six.
These things do not matter because he will achieve them eventually.
Therefore, focus on helping him learn the things that really matter - being happy, sociable, kind, thoughtful, inquisitive, honest, loving, articulate, brave, able to handle both success and disappointment.