I think the bottom one has the best timing, but I'd push it even more - faster strike, slower return. I'd hold on the most extended position longer.
I also recommend that the wind up bring the knife further back, and the attack push it further forward. The silhouettes in all of these are very weak because the knife barely comes forward of the body. Twist the body, have not only the knife, but even the arm come out in front of the torso.