From a Washington Post story by Tyler Pager and Michael Scherer headlined “Inside the final days before Biden announces his reelection bid”:

By the time Air Force One returned from Ireland in the pre-dawn hours of April 15, President Biden’s plans to announce his reelection campaign were already in motion.

A videographer soon met him in Rehoboth Beach, Del., where Biden spent the weekend, after arriving in Dover at 2:26 a.m. with his sister, Valerie, and his son, Hunter. The president shot parts of the launch video over the next two days before returning to the White House on Sunday night, according to people familiar with events, who like others in this story requested anonymity to describe private conversations.