Order of events, as I already covered is Luffy's fist already stretched coming to attack Lucci > a shot focusing on Lucci's fist now imbued with buso. Again, I don't know which version of the chapter you've read where Lucci attacks first or Luffy reacts to Lucci and then chooses to attack but it doesn't exist.
The issue here isn't that I don't understand what you're explaining, it's that what you stated isn't what happened as I brought up in my
previous post. And for Lucci to have even reacted and matched Luffy's attack at the same time he would have needed relative speed to Luffy and not a 16 times difference that's currently listed on the profile.