I would also recommend you taking a look at free opensource
flash preloader component, which may simplify the loading process for you instantly.
It's pretty simple to use. If you want to load an image - you may place preloader instance at a stage and provide the path to image in the parameters and it will be automatically loaded, displaying a loading animation, which you also can simply customize. So you need to write no code at all to load your images and have a preloader for them.