Enemy offset, gallaga style game (space invaders)

So i have a Galaga style game, where the enemies spawn from a point, fly a loop, and then land in the same location (the end of the animation). this creates an obvious problem, being that the enemies "stack" on each other which makes for easy game play.

So my question is how should i get them to space themselves out along the top of the screen. I can't find a way to get a random number in Itween which seemed promising in the beginning, but I really just don't know how i would go about spacing these out... I'm just as happy to use script instead of Itween, whatever seems like the simplest solution.