Hi, welcome to reefing..can share pic or video of ur tank n sump?
Like most reefers say, ur tank shd b pretty well cycled..btw, do u have a skimmer? U can plan ur fish list n add them in accordingly (look at size, aggressiveness, etc) n slowly (if small fishes <3" can add more together)..do note that some fishes like tangs r best to introduce in together to prevent fighting (introduce in pair work for me)..do not over crowd ur tank..
For FOWLR, u dun need to measure calcium,mg,etc..for me, I dun even measure ammonia,nitrite n nitrate..regular wc will keep those in check..my wc regime is 40-50% 3-4weekly..my water sg is 1.016 n temp 28-30°c..