I know there is a lot of controversy between school teachers and parents on the appropriate age for children to begin writing. At age two, some parents expect their children to begin writing, while some wait until age three.
Montessori believes that there's a period in the child's life when he / she learns skills effortlessly. She called this period The Sensitive Period. There's a sensitive period for language which starts at birth through to age six, during which she believes that at about four and a half, children explode into writing.
However, this doesn't mean that children can not be introduced to writing much earlier. At three and a half some of my children in class who have worked with a lot of pre-writing activities develop their wrist muscles and pincer grip and are ready for writing.
In the part of the world where I live, most parents associate the child's learning to when the child begins to write. Of course this is so wrong because babies start learning even while in the womb and continue right after they are born. There's a lot your child can do way before he / she starts writing. There are also a lot of ways you can contribute in preparing your child for writing.
Here's a few...