How to know when loaded ??

Hi all,
I'm using this to load pictures from an array called "photos" (images are held locally on the server) and it works fine:

var loadListener:Object = new Object();
loadListener.onLoadInit = function(mc:MovieClip) {
mc._x = (Stage.width/2)-(mc._width/2);
mc._y = (Stage.height/2)-(mc._height/2+50);
};
var mcLoader:MovieClipLoader = new MovieClipLoader();
mcLoader.addListener(loadListener);
var nextPhoto:String = photos