Acoustic panels on ceiling

Anyone knows where to place the acoustic panels on ceiling? I am reading conflicting stuff.

I have two 48” by 24” GIK Acoustics 242 panels with ceiling cloud mounting brackets.
Yeah... I have all that, absorption on side wall, absorption and diffusers in front and back wall. Just ceiling missing.

You are saying right above where I sit? Maybe toward the front a bit? Mirror trick does not appear to work for me for ceiling 
I've been in a few concert halls where the panels are "floating" in mid-air. They are suspended by wires. You might try putting on an angle. If I were going to do this (panels on ceiling), I'd put them in the center of the room. YMMV.
In this situation I would contact GIK directly and e-mail them pictures of your room as it is currently  set up. They are very helpful in helping their customers utilize their products.
David Pritchard
I did. They said “put them where the first Reflection points on ceiling are”. I tried the mirror trick (hard on ceiling), and could not see anything