[ruslan_mart]

var hours = 12;
var minutes = 30;

function start() {
   //...
}

var date = new Date;
date.setHours(hours);
date.setMinutes(minutes);

var intervalId = setInterval(function() {
    if(date <= Date.now()) {
         clearInterval(intervalId);
         start();
    }
}, 1000 * 60);