<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment-with-locales.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment-timezone/0.5.23/moment-timezone-with-data.min.js"></script>
</head>
<body>
<span id="date"></span>
<script type="text/javascript">
$(document).ready(function() {
function isToday() {
var $nowInMoscow = moment().tz("Europe/Moscow").format('X');
var $lastSecInMoscow = moment('18:59:59', 'HH:mm:ss').tz("Europe/Moscow").format('X');
return $nowInMoscow - $lastSecInMoscow <= 0;
}
var $text = isToday() ? 'Сегодня в 19:00 МСК' : 'Завтра в 19:00 МСК';
$('span#date').text($text);
});
</script>
</body>