I used to flinch pretty bad too when I first got my BP. My guy is a good eater and always strikes pretty fast. I’ve had him for about 2 years now and I’ve gotten used to it. At first I would rest my arm on the side of the cage like mentioned above. Just do your best to prepare for it and you’ll probably get over it. I also just looked away a few times which made it a lot better. You can try this as long as your snake is a good eater and will come to the mouse himself. Good luck!