need help for a jquery plugin


i have made a counter up plugin and i want to use it in my theme.
but the problem is the plugin start working after the page loding.
and my counter up is quite down from the page.
so i want to start the counter up when it comes to visibla.
how can i do that ?
my jquery plugin is

$('.Count').each(function () {
        Counter: $(this).text()
    }, {
        duration: 5000,
        easing: 'swing',
        step: function (now) {