Least aggressive to most aggressive. Same species add at the same time (within reason). For example, I stocked in this order. Chromis, Midas Blenny, Melanerus Wrasse, Regal Angel, Tangs (4), and lastly the Dwarf Angels (the most territorial). A did roughly a week between fish, longer after the tangs so the bio load wouldn't crash the tank. Don't get me wrong there was some aggression but it was minimal. If you can when you get into the more expensive fish acclimate until the lights go out in the tank, add them in the dark, and overfeed the next morning. Tangs and angels need to see their food supply isn't impacted by the new fish and they usually leave others alone after a day or two.
I have 2 dwarf angels, plus a Regal (not the best idea...) and 4 tangs (also not the best idea) but it worked, stick to your plan, don't deviate because of a fish sale or impulse buy. MAKE SURE THE FISH ARE HEALTHY AND EATING, and good luck. Slow and Steady...