My understanding of ikkyo is that it is a controlling move. From ikkyo you can go to almost another technique. I have found that it is really important to take your uke's balance, then control your uke. I am not sure why O'Sensei made that particular movement and called the movement ikkyo. (By the way, ikkyo means "technique number one") Maybe he felt that taking control was one of the more important things in aikido - I don't know.
Try controlling the uke by keeping your one-point above the arm and extending your ki down. I am not sure how far along you are in aikido, but just remember that it takes a really long time to understand the underlying principles to the techniques.