On July 22, 2015, Lilac Corporation purchased 25% of the Coffee Corporation stock outstanding. Lilac Corporation purchased an additional 40% of the stock in Coffee on March 25, 2016, and an additional 20% on May 2, 2016. On September 23, 2016, Lilac Corporation purchased the remaining 15% of Coffee Corporation stock outstanding. For purposes of the § 338 election, on what date does a qualified stock purchase occur? What is the due date for making the § 338 election?