Three of my children had it at the ages of 4 yrs, 2 yrs and 6 mo. The 6 mo old was totally breastfed and the doctor didn't think she would get it or it would be a mild case. It was a bad case with pox in her mouth and vaginal area. She still has scars even though she never scratched.
Please don't assume that chicken pox is a benign disease for infants. My children were pretty sick for about a week.
jmh