Just having a quick read of "Flight Fantastic - the Illustrated History of Aerobatics" by Annette Carson.
Lt Wilfred Parke RN is credited as the first person to recover from an accidental spin in an Avro G on 25 August 1912 at Military Trials on Salisbury Plain. His eventual use of right rudder stopped the left hand spin.
In another chapter, Harry Hawker is credited as likely being the first person to deliberately spin an aeroplane and recover: on 27th June 1914, he spun deliberately in a Sopwith Tabloid, failed to recover and crashed with damage to the machine and later said "I know what I should have done... I'll go up and prove my theory", took the repaired Tabloid up and did just that!
Carson's references were "Early Birds" by H C Miller (Angus & Robertson, 1968) and "The Brooklands Story" by Howard Pixton, AV Roe & Co 1955.
There's more! Carson's book is a great read if you can get hold of a copy: published by Haynes in 1986.
Treadders