might want to specify which hk, the last hk you’re already in flyscreen so you shouldnt be moving back at all. so i’ll assume you’re talking about the 3rd hard kick in the combo, you’re either doing it too fast or too slow so experiment with different speeds between the hard kicks. also, for me its easier to s.hk /\ sj.hk ad/df hk / c.lp normal jump straight up j.lk, d+mp, j.mk, j hk.
to time the lp, you want the person to land on your lp as in you dont want any part of their body below your lp when you hit them. it also depends who you do it on, for mags/cable size you can do it your way, but also still able to do it the other way i mentioned.