Here's what I do with new shooters...

I go over safety protocols etc... then I start by moving them right up to the target which is against a back stop so they can't miss. Like 5 ft away. I give them the pistol and tell them to dump the whole mag, as fast as they can, into the target, all while focusing on tracking the front sight. We are pushing for speed... no regard to accuracy. We do that 3 or 4 times and then move back for slow shots. It's not 100%, but it works most of the time.

My theory as to why it works: you're shooting so fast that you don't have time to keep flinching, so you break the habit through volume. And after 4 mags of tracking the bobbing front sight you adjust to the shock and impulse of the whole thing. The surprise is gone.

Try it. See if it works for you. Think like you're trying to control a machine gun. You can't keep blinking.