Question: What year did Britain's Royal Flying Corps choose watches made by the company who later made the Electroquartz as their official timekeepers?

Context articles: RAF Manywells Height
Omega SA
Omega Electroquartz
RAF Middle East Command
Archibald MacLean
Herbert Bellerby
Cuthbert Hoare
No. 11 Squadron RAF
RAF Mousehold Heath
List of Royal Flying Corps generals

Royal Air Force Manywells Height (also known as Royal Flying Corps Manywells Height, Royal Flying Corps Cullingworth & Royal Air Force Cullingworth) was a grassed airstrip in use as Home Defence during the First World War.
 The site was just south of the village of Cullingworth which is south of Keighley and north west of Bradford in West Yorkshire.
Omega SA ( ; ) is a Swiss luxury watchmaker based in Biel/Bienne, Switzerland.
 Britain's Royal Flying Corps chose Omega watches in 1917 as its official timekeepers for its combat units, as did the American army in 1918.
 Omega watches were the choice of NASA and the first watch on the Moon in 1969.
 Omega has been the official timekeeping device of the Olympic Games since 1932.
 James Bond has worn it in films since 1995; other famous Omega wearers, past and present, include John F. Kennedy, Prince William, George Clooney and Buzz Aldrin.
 Omega is owned by the Swatch Group.
The Omega Electroquartz was introduced in 1969 as the first production Swiss quartz watch.
 It was the collaboration of 20 Swiss watch companies and the movement was utilised by Rolex, Patek Phillipe and Omega SA amongst others.
 The Beta 21 movement used in the Electroquartz was accurate to 5 seconds per month, far better than any automatic or manual wind movement of the day.
Middle East Command was a command of the Royal Air Force (RAF) that was active during the Second World War.
 It had been preceded by RAF Middle East, which was established in 1918 by the redesignation of HQ Royal Flying Corps Middle East that had been activated in 1917 although a small Royal Flying Corps presence had been operational in the region since 1914.
Archibald Campbell Holms MacLean, {'1': ", '2': ", '3': ", '4': "} (23 October 1883 – 30 April 1970) was an officer in the Royal Scots, Royal Flying Corps and Royal Air Force.
 MacLean attended the Royal Military College, Sandhurst, before he was commissioned into the Royal Scots.
 He transferred to the Royal Flying Corps in 1913 and during the First World War served as a squadron leader and wing commander before taking up senior training and staff appointments.
 In April 1918 he transferred to the newly formed Royal Air Force and was subsequently promoted to brigadier general just after the end of the First World War.
Sgt. Herbert Bellerby (29 August 1888-23 September 1916) was a Royal Flying Corps pilot of World War I.
 He was a cavalry officer before joining the 27 Squadron in the Royal Flying Corps, flying a Martinsyde G.100 elephant plane.
 Bellerby is mainly known for being the second kill of Manfred von Richthofen, AKA The Red Baron, over Cambrai Road, near Bapaume.
 Richthofen was using an Albatros D.II.
Brigadier-General Cuthbert Gurney Hoare {'1': ", '2': ", '3': ", '4': "} (21 January 1883 – 31 January 1969) was an officer of the British and Indian Army, who served in the Royal Flying Corps during World War I, and as the commander of Royal Flying Corps Canada.
No. 11 Squadron of the Royal Flying Corps was formed at Netheravon in Wiltshire on 14 February 1915 for "fighting duties", receiving two seat pusher Vickers Gunbus fighters in June, and deploying to France on 25 July 1915.
 Since all previous squadrons (Royal Flying Corps or other nations) were reconnaissance or army co-operation units, 11 can make a claim to be the oldest dedicated fighter squadron in the world.
 The squadron has had the honour of having two Victoria Cross winners serve in the unit.
The area of Norwich between the Salhouse and Plumstead roads (outside of the outer ring road) was originally the Cavalry Training Ground and then became the Royal Flying Corps Mousehold Heath aerodrome where Boulton Paul, among other manufacturers, passed over the aircraft they made for service.
 It was sometimes known as Norwich aerodrome by the Royal Flying Corps before it became Royal Air Force Station Mousehold Heath in April 1918.
The following is a list of senior Royal Flying Corps generals.
 While officially general officers are not considered to belong to any regiment or corps (simply being "late" of their erstwhile regiment), in practice almost all the general officers to hold a Royal Flying Corps-related appointment gained their promotion to the general officer ranks in that appointment and remained in such appointments until the creation of the Royal Air Force on 1 April 1918.
 Royal Flying Corps generals then became Royal Air Force generals.