Countdown timer is bringing the wrong value

I copied a function from W3Schools to create a regressive timer. But the end date will be dynamically passed, in case the end date would be 09/06/2018

My question is how to pass the end date in a way that function new Data().getTime(); does the conversion correctly.

At the moment it is returning me like this:

Thecallingfunction:

$.get("/Home/ConsultarCicloData", null, function (data) {
                if (data != null && data != undefined) {
                    var objeto = JSON.parse(data);
                    $('#lblCiclo').text(objeto.ciclo);
                    $('#lblData').text(objeto.dataIni)
                    $('#lblDataFim').text(objeto.dataFim);

                    Cronometro(objeto.dataFim, objeto.ciclo);
                }
            });

 function Cronometro(dtFinal, ciclo) {
            var d, m, a;
            var dtF = dtFinal.replace("/", " ").replace("/", " ");
            dtF = dtF.split(" ");
            d = dtF[0];
            m = dtF[1];
            a = dtF[2];
            var countDownDate = new Date(a,m,d).getTime();

            // Update the count down every 1 second
            var x = setInterval(function () {

                // Get todays date and time
                var now = new Date().getTime();

                // Find the distance between now an the count down date
                var distance = countDownDate - now;

                // Time calculations for days, hours, minutes and seconds
                var days = Math.floor(distance / (1000 * 60 * 60 * 24));
                var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
                var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
                var seconds = Math.floor((distance % (1000 * 60)) / 1000);

                // Output the result in an element with id="demo"

                document.getElementById("demo").innerHTML = "Faltam " + days + " Dias " + hours + " Horas "
                    + minutes + " Minutos para o fechamento da Semana " + ciclo;

                //If the count down is over, write some text 
                if (distance < 0) {
                    clearInterval(x);
                    document.getElementById("demo").innerHTML = "";
                }
            }, 1000);

        }