How long to wait to add corals?

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So....... I have had my 10 gallon nano up and running for about 7-8 weeks now and have 3 small fish (oce clown, purple firefish and yellow head jawfish)(i know....probably too many, but I don't mind doing the frequent water changes). I am wondering when I should start adding corals, and what would be best to start with? Any words of wisdom?