I think my first coral were some Paly's. They like somewhat dirty water and can handle the new tank blues. If I remember correctly, I added a Kenya tree early on too. Don't lol! Whatever you add, make sure it's cheap. Hopefully a LFS has $5 frags. Start with a couple of those.
For CUC, as soon as you start seeing diatoms or film algae add a small crew. I haven't caught the size of your tank but go smaller than what online suggestions usually are. I see you plan on adding CUC piecemeal. More expensive but less likely to have die off. Try to include a diverse mix of CUC. I have some turbo, nassarius, nerite, cerith, dwarf cerith, a few chitons, and even a fighting conch in my 220. Love the chitons, they destroy algae on the rocks.
Good luck and keep asking questions!