The first day of the first year of a nengÅ started whenever the emperor decided . This first year continued until the next lunar new year , which is understood to be the start of the nengÅ 's second year . In historical practice , the first day of a nengÅ starts whenever the emperor chooses ; and the first year continues until the next lunar new year , which is understood to be the start of the nengÅ 's second year .