The incubation period of chickenpox is 10-21 days, mostly 14-16 days, so contact with chickenpox patients, if the infection is generally the fastest 10 days or so onset. The first thing you need to do is to get a good idea of what you are getting into. If there is no disease after 3 weeks, it basically means that you are not infected. The main way of transmission of chickenpox is through saliva droplets, but also through contact with chickenpox virus contaminated clothing, bedding, toys, utensils and so on.