How to make an object wait until it finishes moving?

I'm working in unityscript and have a section of my code where the object moves up, right, then down. However, when I run the code, it skips to moving down. I tried putting in a yield WaitForSeconds(), but it didn't work. How can I make the code wait until a movement has finished before moving to the next? This is what the section of code looks like:

 rigidbody.MovePosition(rigidbody.position + Vector3(0,20,0) * Time.deltaTime);
 rigidbody.MovePosition(rigidbody.position + Vector3(30,0,0) * Time.deltaTime);
 rigidbody.MovePosition(rigidbody.position + Vector3(0,-20,0) * Time.deltaTime * 2);