You need to specify the hour in the Date class like this.

Eg.

PHP Code:
var year:Number 2013
var 
month:Number 1
var 
day:Number 3;
var 
hour:Number 8;

var 
finalDate:Date = new Date(year,month-1,dayhour); 
I’ve written a post about the Date countdown using xml which might help you. Also, take a look at the AS3 Date class for more information.