Drugpunker,
 
 
 
<!DOCTYPE HTML>
<html>
<head>
    <title>Untitled</title>
    <meta charset="utf-8">
    <style type="text/css">
        .time, input {
            background: rgba(102, 255, 51, 1);
            width: 80px;
            height: 30px;
            display: block;
            text-align: center;
        }
    </style>
    <script>
        function countdownTime(elem) {
            var bet_time = new Date;
            bet_time = bet_time.getTime() + 20000;
            window.clearTimeout(elem.timer)
            function calculate(elem) {
                var now_time = new Date;
                now_time = now_time.getTime();
                var seconds = Math.ceil((bet_time - now_time) / 1000 * 1);
                if (seconds > 0) {
                    residue = seconds < 10 ? "0" + seconds : seconds;
                    elem.innerHTML = "00:00:" + residue;
                    elem.timer = setTimeout(function () {
                        calculate(elem);
                    }, 1000);
                } else {
                    elem.innerHTML = "Поехали";
                }
            }
            calculate(elem);
        }
        function clickTimerButton(elem) {
            return countdownTime(elem);
        }
        window.onload = function () {
            var span = document.querySelectorAll('.time');
            for (var i = 0; i < span.length; i++) {
                var el = span[i];
                var button = document.createElement('input');
                button.onclick = (function (span) {
                    return function () {
                        clickTimerButton(span)
                    }
                })(el);
                button.type = 'button';
                button.value = 'Жмак!'
                el.parentNode.insertBefore(button, el.nextSibling);
                button.click()
            }
        }
    </script>
</head>
<body>
    <span class='time'></span>
    <span class='time'></span>
    <span class='time'></span>
    <span class='time'></span>
</body>
</html>