The exact timing for this link is when Hazama grabs them with Jakou, hits them on the wall, they wallbounce and when they make a small floor bounce after hitting the ground, jump and do j.6D. Remember that you can't press 6 to jump so make sure to press 9, 7 or 8 and then make a quick quarter circle (Assuming you do 8)to 6 and then press D.
This is something you must constantly adjust to with your own judgement if you've had enough experience with Hazama's combos but in general, what you want to do is make the 4D~A part of the combo hit in front of their stomach and preferably not under their legs because that means you either have to delay the j.8D a little more or depending on how you did the combo, you screwed yourself. Good thing to keep in mind is that if 4D~A hits them under their legs, usually a j.8D is the thing that will save your combo. But j.8D isn't the norm to use on most characters. It's almost always better to do j.7D and it reduces the possibility of getting the less hitstun version of D. The issue also might be because of 5C > 2C part of the combo. Make sure you always cancel 5C on the second hit and delaying 4D~A is recommended.