steppermotor with big easy stepper shield and accelstepper library

Is it not possible to complete the code after "for (int shot=0 ; shot < TotalShots ; shot++){}" before counting another shot?

Yes, it is. You need a do nothing until mechanism in the loop() function, not an if mechanism.

    for(int shot=0 ; shot < TotalShots ; shot++)
    { 
       stepper.moveTo(pos);   
       stepper.run();
      
       while (stepper.distanceToGo() != 0)
       {
          // Don't do a thing. The stepper ain't there yet.
       }

       // Now, the stepper is where you want, so take a picture
       delay(1000);  
       Serial.println("number of shots"); 
//    digitalWrite(SHUTTER_PIN, LOW);
//    delay(2000);  // take shot
//    digitalWrite(SHUTTER_PIN, HIGH);

       stepper.setCurrentPosition(0);  
    }