Your tank is like a baby, yes it's done it's cycle but you need all the good bacteria to become established. Right now there's just no more die off. I'm not good at the scientific stuff
, but I know with some corals if you add to soon, they will just die and frustrate you. You are going to have swings in your parameters, you need to learn about keeping the tank stable for ca, mag and alk. I'm on my second tank and find the first 9 months to a year to be the most challenging, after that things seem to stabilize. This hobby is about going slow, start with easy corals, see how they do, then move into the harder ones. Learn to recognize when things are thriving and when something is "off". Add your cuc and a couple of fish to start. Let the tank get used to that bioload and add another fish.