Keypoint of Pinan Sandan

Details of the movements

After executing Yonhon nukite in Junzuki dachi (is Chudan, Nukite appears higher due to camera angle), do Mawatte and place the back of your right hand on your tailbone. It is important that you press your hip forward and that you bend your front knee sufficiently, but not too far. As a matter of formality, keep your left fist (Hikite) during the movement at the side of the chest. Make sure to lean forward correctly. Then, move backward and turn your body sharply as you execute Tettsui uchi in Shiko dachi.

The body movement between the leaning stance (cross between Junzuki and Junzuki no tsukkomi dachi) and Shiko dachi can be done in the different ways, as mentioned below. Without knowledge of Karate, just by seeing the body movement and analysing that, you could come to the following possibilities (emphasis on the movement of the upper body):

1: Get straight up as soon as possible, move and execute Tettsui uchi. 
2: Get straight up gradually, so straighten your body throughout the movement and finalise this when you execute Tettsui uchi and take Shiko dachi.
3: Lean forward as long as possible and straighten your body at the last split second as you execute Tettsui uchi.

Which way do you think is the correct way? Sakagami sensei uses this way of teaching in class from time to time and likes to get you thinking for yourself. Therefore, I would like to share his method and give you the answer in the video.

What is the correct way?