I'm 26 weeks pregnant, and haven't yet told my DS (age 3.5). My logic is that he has no concept of time - asks often when Christmas is coming, and says things like "is it later yet", "when will it be yesterday". I'm concerned that if I tell him I'm expecting a baby, he'll wonder every day if today's the day it's coming. He doesn't seem to have noticed my huge belly - boys eh!
I know there's no right answer to this, as all children are different. But I just wondered what everyone else had done.