Im said the upcoming summit will be focused on key issues including the denuclearized Korean Peninsula and the establishment of a permanent peace.
North Korea's state-run media declared Thursday that this week's breakthrough inter-Korean summit was made possible due to leader Kim Jong-un's "passionate love" for the peninsula's people.
Nuclear explosions release enormous amounts of heat and energy, and the North's largest test in September was believed early on to have rendered the site in northeastern North Korea unstable.
Kim will become the first North Korean leader to step on South Korean soil since the end of the 1950-53 Korean War, which ended with an armistice instead of a peace treaty, Efe news reported.
Kune Yull Suh, a professor of nuclear engineering at Seoul National University, warned a year ago that further tests could threaten to cause a volcanic eruption at Mount Paektu, which is about 100 kilometers (60 miles) away.
However, he added it was yet hard to determine to what extent the two leaders will agree on, in regard to denuclearization.
"(Seoul) takes the move as a sign that the North is not considering just the inter-Korean summit, but looking ahead to the US-North Korea talks, and global cooperation that will follow".
The delegations will have separate lunches, Im told a briefing, with the North's group crossing back to their side of the border to eat.
Seoul says North Korean leader Kim Jong Un and South Korean President Moon-Jae-in will plant a tree together and inspect an honor guard after Kim walks across the border for the leaders' historic summit.
"We are thinking it could be called the "Panmunjom Declaration", Im said. A banquet and farewell ceremony will follow in the evening before Mr Kim returns to the North.
The list of Moon's entourage includes Im Jong-seok, presidential chief of staff; Chung Eui-yong, top national security advisor for the president; Suh Hoon, chief of the National Intelligence Service (NIS); Foreign Minister Kang Kyung-wha; Defense Minister Song Young-moo; Unification Minister Cho Myoung-gyon; and Jeong Kyeong-doo, the head of South Korea's Joint Chiefs of Staff (JCS).
The mood of pessimism lifted in February, in the subzero temperatures of the Winter Olympics, as North Korean athletes, cheerleaders and Kim's sister descended on the South Korean host city, Pyeongchang.
"We did not expect this".
On Saturday, North Korea announced it will close its nuclear testing facility and suspend nuclear and intercontinental ballistic missile tests - a move welcomed by Trump as "big progress" - and which comes ahead of a planned summit between him and Kim.