The ultra rare K → πvv process is one of the theoretically cleanest meson decay where to look for a stringent test of the Standard Model (SM). The NA62 experiment at CERN SPS is designed to measure the branching ratio of the K+ → π+ vv decay with 10% precision. After commissioning, in 2016 first data set good for physics has been collected. The data taking is foreseen till the LS2 at the end of 2018. Results obtained with the full 2016 data sample will be presented togheter with prospects for 2017 and 2018 data sets.