Indeed the 3rd word, but it has not a fixed place in the string, so I used the index of the spaces:
console.log (SysInfo.dateHuman); // just to show dateHuman
var temp = SysInfo.dateHuman.slice(SysInfo.dateHuman.indexOf(' ')+1);
temp = temp.slice(temp.indexOf(' ')+1);
var Maand = temp.slice(0,temp.indexOf(' '));