Can you please take a look at following code and let me know how I can avoid the delay on only FIRST time of this counting down process?

As you can see the counter works fine but there is a delay on first time starting.

1.     var sec = 20;
2.     var timer = setInterval(function() { 
3.        $('#box').text(sec--);
4.        if (sec == -1) {
5.           $('#box').css('color','blue');
6.           clearInterval(timer);
7.        } 
8.     }, 1000);

1.     <div id="box">20</div>

Demo

Thanks