Couple of thoughts:
We all get the flinchies, sooner or later, and until you've shot a lot (!), they make regular appearances. Even after you've shot a lot (!) they'll still show up from time to time.
If you have an autoloader, get some snap caps that fit, and mix them into your mags. It's also good practice to integrate this in as a failure drill.
When dry firing, balance a penny on your front sight, and practice trigger control until you can do it reliably without dropping the penny.
Reality check your hearing protection, make sure you've got at least -25 db, and preferably closer to 30 or better.
Mostly, though, its a matter of mentally over riding your natural reactions. Feel free to flinch away, AFTER the hammer has dropped and the round discharged. You can actually zen it out: "I will not flinch until after the hammer has dropped...I will not flinch until after the hammer..."