The fish you don't have to worry about, you can add them with the lights out or on, they will normally just run and hide.
As for the corals, you need to find out what lighting they came from, if it was LEDs then your all set, just place them. If not, then start them out at the bottom of the tank, with LEDs at 20%, move up 10% a week until disired strength is reached, normally around 60-70%. If you already have corals in the tank, put your new coral kind of in a shaded place for the week, and slowly bring it out into full light, then after a few weeks you can bring it up the rock ladder.