Need help with Aatrox's E interactions

With the title I refer to the AD steroid, and how does it work with the other abilities.

If I cast it before the first cast of Q, will it benefit all 3 casts of that same ability? If I cast E during the execution of Q, does it amplify the damage of Q? If I cast it before the second or third cast of Q, will it boost one or both of those casts? Or neither?

55 bonus AD is juicy, but I want to know in what circumstances I'll actually benefit from it, rather than wasting it 90% of the time. Of course it's way more simple if we're talking about AAs, but now you want to use Q to deal as much damage as possible.