whats observed first the sound of the shot the flash of the shoot or the result of the shot?

The human brain can only detect so much so quickly. It all happens so fast the human brain won't be able to distinguish each in their own time so as for as you know it will all happen at once if this takes place at close range. At long medium range the flash will be more noticeable and the bullet with (at this distance would be a crack rather than a boom,) the crack would blend with the bullet. At long range, (assuming you can see it) the flash would be perceived, then the bullet, and at a certain range the bullet would be subsonic so the sound would follow an instant after the bullet.

The speed is the determining factor.

Light has the highest speed so it arrives first.

The speed of the bullet is often faster than sound so the bullet arrives next.

And finally the sound arrives.

In the first world war newbies would flinch when they heard a bullet whizzing overhead.

They were reassured with the statement " you will never hear the bullet that kills you"

Because by the time you hear the bullet it has already passed by.

Since light travels somewhat faster than sound or bullets you would see the flash first