What’s the first tank dwellers??

Ok so my new tank is leveling out finally and planing on retesting tomorrow and if there 0 I’ll do my first water change. Not bad about 4 weeks set up so far. I did purchase a live rock with coraline algae to seed the tank after about a week and it appears to of spread rather fast, not purple but kind of a brown color across all of the base rock and the purple of the live rock is hardly noticeable any longer and the same brown color was under the coraline algae So that got me thinking what should be my first tank mates? Clean up crew members or a fish? I’m not sure. I wouldn’t think I would have anything to clean up yet that’s for sure so thinking a fish makes better sense but thus why I’m here.