SA Newbie so please be gentle. Have never owned or fired a SA Pistol so don't want to mess up a New CZ Custom B SA Lower. Should the Safety be engaged while the slide (bolt) is still locked "back"? Then release the slide (bolt ) with the Safety engaged ? Or release first and then engage the Safety ? Does it work the same way with a "Normal " slide such as 9mm or .40 S&W ?