How do I start an animation at a particular point when I am using a list of prefabs?

I have created a list of prefabs for Galaxian style baddies in a game like this:

public List aliens1Group = new List ();

and then for each baddie:

aliens1Group.Add (Instantiate (Resources.Load ("Alien1Prefab")) as GameObject);

Each baddie has a 4 frame animation. How do I get some of them to start at different positions in the animation.