Question: Elena and the Secret of Avalor was a crossover containing a series that premiered on Disney Channel on what date in 2016?
Sentence (from "Elena and the Secret of Avalor"): Elena and the Secret of Avalor is an American computer-animated musical fantasy adventure crossover television movie between two Disney television series, Disney Junior's "Sofia the First" and Disney Channel's "Elena of Avalor", taking place before the latter series.
Relevant evidence: Yes