This was fast. To be safe, start with the small invertebrates, that you are planning to keep, something like snails or hermits - for gradual rising bioload, give them some food. Then some shrimp, if in 4 days no ammonia or nitrites. Then more, then some corals, then fish.
Right now may be no organic matter in the tank for bacteria to process, and adding fish, that produces waste and a food for it - may be too much for a small existing population of bacteria to handle. Could be OK, especially adding in the same time some bacterial culture, like Stability. But - it could be boring for the fish to be in the lifeless tank.