When did the manager take over for the manager that left on August 20, 2008?
CREATE TABLE "managerial_changes" (
  "team" text,
  "outgoing_manager" text,
  "date_outgoing" text,
  "reason_of_departure" text,
  "replaced_by" text,
  "date_of_replacement" text
);
SELECT "date_of_replacement" FROM "managerial_changes" WHERE "date_outgoing"='august 20, 2008';