First time I shot over my pup ....took her out and planted hen phesants, when she flushed them I just fired my shotgun away from her just up in the air, she stopped stood and and looked at me, I called her, she came and I praised her for it. After several more times of doing this, before she would flush anymore birds, she would turn quick and look at me to say, "Are you going to shoot?" and I would, never aiming at the bird.
I'm not a dog trainer by no means, but this is what works for me.