Setting the frame upon creation of instance

For my game, I'm generating clouds with a random Y value that scroll to the left. Because they're rather big images, I combined them all as frames of one sprite. When a new cloud is spawned, I want to randomize the frame it draws on the screen, but I have no idea how I can do that without randomizing it for every cloud that is already spawned.

So in short, I'm asking this:

Is there a way to set the animation frame for an instance when it is created?

I appreciate your help.

Any action in an event which runs after a 'Create' will run only on the created object, so simply add it there .

Oh, I didn't know that! It totally worked and got me out of a heckload of trouble

Because they're rather big images, I combined them all as frames of one sprite.

This doesn't make it use any less data, it's only for convenience sake.