Background: Harry was born in the Lindo Wing of St Mary's Hospital in Paddington, London, on 15 September 1984 at 4:20 pm as the second child of Charles, Prince of Wales, heir apparent to Queen Elizabeth II, and Diana, Princess of Wales. He was baptised with the names Henry Charles Albert David, on 21 December 1984, at St George's Chapel, Windsor Castle, by the Archbishop of Canterbury, Robert Runcie. His godparents are Prince Andrew (his paternal uncle); Lady Sarah Armstrong-Jones (his paternal cousin once removed); Carolyn Bartholomew (nee Pride); Bryan Organ; Gerald Ward (former officer in the Household Cavalry); and Celia, Lady Vestey (nee Knight).
Context: On 17 March 2015, Kensington Palace announced that Prince Harry would leave the Armed Forces in June. Before then, he would spend four weeks throughout April and May at army barracks in Darwin, Perth and Sydney whilst seconded to the Australian Defence Force (ADF). After leaving the Army, while considering his future, he would return to work with the Ministry of Defence, supporting Case Officers in the Ministry of Defence's Recovery Capability Programme, working with both those who administer and receive physical and mental care within the London District area in a voluntary capacity.  On 6 April 2015, Prince Harry reported for duty to Australia's Chief of the Defence Force, Air Chief Marshal Mark Binskin at the Royal Military College, Duntroon in Canberra, Australia. Harry flew to Darwin later that day to start his month-long secondment to the ADF's 1st Brigade. His visit included detachments to NORFORCE as well as to an aviation unit. While in Perth, he trained with Special Air Service Regiment (SASR), participating in the SASR selection course, including a fitness test and a physical training session with SASR selection candidates. He also joined SASR members in Perth for live-fire shooting exercises with numerous Special Forces weapons at a variety of ranges and completed an insertion training exercise using a rigid-hull inflatable boat. In Sydney, he undertook urban operations training with the 2nd Commando Regiment. Training activities included remotely detonating an Improvised Explosive Device (IED) and rappelling from a building. He also spent time flying over Sydney as co-pilot of an Army Black Hawk and participated in counter-terrorism training in Sydney Harbour with Royal Australian Navy clearance divers.  Harry's attachment with the ADF ended on 8 May 2015, and on 19 June 2015 his career with the Army ended.
Question: When was he Seconded to the Australian Defence Force?

Answer:
On 6 April 2015,