What is the start date with Luke Jacobz hosting and Dannii Minogue as a winning mentor?
CREATE TABLE "series_summary" (
  "series" text,
  "start" text,
  "finish" text,
  "winner" text,
  "runner_up" text,
  "third_place" text,
  "winning_mentor" text,
  "main_host" text
);
SELECT "start" FROM "series_summary" WHERE "main_host"='luke jacobz' AND "winning_mentor"='dannii minogue';