ShinobiBrown
[10] Knight
You can probably tiger knee the motion. Do the quarter circle motion into upback, and hit K as soon as you leave the ground. The idea is that you have a few frames after doing the quarter circle motion to actually start the special, so you start the special motion on the ground, jump, and activate it in the air.
Tiger Kneeing BK gives you a HJC'd ground BK. It doesn't give you an instant aerial BK and if it does, the timing is weird or super strict resulting in a simple Jumping HK if you wait for her to leave the ground. Even doing 214789 doesn't give you an instant aerial BK (that's the method I use to get instant Dive Kicks with Cammy). So I've been doing 963214 to do BKs as soon as I leave the ground. I only TK the motion if I want a HJC.