AS2 - Need help with setInterval

Hello, I am creating my first AS2 game, and have used the Vertical Shooter tut to get me started - http://www.kirupa.com/developer/actionscript/vertical_shooter.htm

The main difference is that I am trying to catch falling objects, which need to all start falling from the same start height (contolled by y co-ordinate - I have managed to do this) but I also need them to start at phased intervals - at the moment they all start to fall at the same time. I am thinking I should be able to do this by using setInterval to control when each object starts to fall e.g. every 2 seconds, but am not sure where to insert it in my code.

Does this sound like the right approach? Or is there another pause function that I could be using?

I can post my code if needed.

Thanks