I have a friend whose son possibly has chicken pox. I plan on exposing my kids but need to know if it "sticks" at what point will they in turn be contagious. Is it at the first sign of symptoms or anytime between exposure and development of symptoms. I need to know so I can plan how long and when they should be kept home from school. I don't want to knowingly have my kids contagious around other kids. I don't think that is a right thing to do. Thanks!
The infectious period lasts from about three days before the rash appears until all the blisters have formed scabs. The incubation period between being infected with chickenpox until the disease breaks out and symptoms appear is 10 to 20 days.
From that I presume you would have to consider them possibly contagious from a week after exposure till either the 20 days have past or they have caught and got over the chicken pox.