Question: When did Ottmar Hitzfeld start as head coach for Borussia Dortmund?
Paraphrase: When did Ottmar Hitzfeld begin as head mentor for Borussia Dortmund?
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q41420 p:P286 ?s . ?s ps:P286 wd:Q44478 . ?s pq:P580 ?value}