I taught Prep for two years before having DS and Preschool for several before that. I liked my students to be able to write their name but it's not prerequisite.

Your DS can copy his name so that's a great start. From there you can always try alternative ways of writing it: in sand with a stick or with a paint brush and water on cement. Just funs ways to help it sink in.....

Try to make sure he is aware of what he is copying, some children can copy writing until the cows come home but if they aren't aware of what they have written than I see little point. You can encourage this by getting him to type his name on the computer finding the letters himself, scourring through magazines looking for letters that are the same as in his name (cut them out and paste) or by making the letters with playdough so he starts to understand how they are formed - talk about curves, straight line etc..

Do a search for QLD Beginners Font, you will find some examples and best of luck with preparing your DS for prep!