2015 Aug – Nov (1Y8m): apply the PN class of YR2016/17, school year starts from Sept 2016 (2Y8m)
2016 Aug – Nov (2Y8m): apply the K1 class of YR2017/18, school year starts from Sept 2017 (3Y8m)
Since 2Y can attend N class, so you may check with the school if any PN admission at Jan 2016 (2Y). Then, K1 admission at Sept 2016. (2Y8m)