I've made you a fiddle based on your code: http://jsfiddle.net/959TT/5/
What you're missing is this:
createjs.Ticker.addEventListener("tick", function(){stage.update(event);});
This line causes the stage to update continuously (like frames in movies).
In your case, you were updating the stage only after both tweens are finished, so it looks like nothing happens before that.
Updating stage can be a costly operation, so you might consider adding and removing "tick" listener depending on the situation, like this:
function tickHandler(event){
stage.update(event);
}
When you need tween animation:
createjs.Ticker.addEventListener("tick", tickHandler);
After all animations finished:
createjs.Ticker.removeEventListener("tick", tickHandler);
stage.update(); // to make sure everything is drawn
EDIT: I've updated fiddle for clarity, also it turns out you need to call stage.update() one more time after removing "tick" listener.