I know chicken pox can take up to 21 days to appear after exposure to the virus, but is that normal in toddlers/babies, or does it usually develop more quickly than that? My 3 year old was exposed a couple of weeks ago at nursery - no signs of anything yet. Have also got a 7 month old who will be in the firing line if 3 year old gets poorly... and a holiday booked for mid May. Last holiday 3 year old got taken into hospital in an ambulance with a severe chest infection. The time before he had a horrible tummy bug. We're cursed.