A twelve-mоnth оld bоy wаs in for his one-yeаr heаlth supervision visit 3 days ago, and he received the MMR and HepB and Hib vaccines at that time. His mother chose not to give the Varivax (chickenpox) vaccine because she wanted him to get the “real thing.” She has since changed her mind and wants to come back for the vaccine as soon as possible. The appropriate timing to give this vaccine is: