On July 20, 2017, Lilac Corporation purchased 25% of the Coffee Corporation stock outstanding. Lilac Corporation purchased an additional 40% of the stock in Coffee on March 22, 2018, and an additional 20% on May 2, 2018. On September 25, 2018, 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?