DS could write his name at about 3.25. He will be four in a couple of weeks and he can easily write anything that I tell him how to spell. He frequently asks how to spell full sentences, and I spell them out to him while cooking.
He can also write simply CVC words on his own. He can draw a dog and write "Max" under it by sounding it out.
As I sit here though, he is currently snuggled up next to my whimpering because he has remembered a pair of tennis shoes he had when he was two and wants to get them back insisting his feet are now small enough for them. So, while he is definitely ahead in some areas, I am quite sure he is behind in some as well. Or maybe all four year olds are ridiculously irrational beings.