Pilot Officer Billy Fiske joined 601 Sqn in July 1940; his first flight with 601 is logged as "Type solo" which suggests that he had not flown a Hurricane (or any other front-line type) before.
https://www.rafmuseum.org.uk/images/...uly-1940LG.jpg His first patrol was flown six days later, by which time he had some 10 hours on Hurricanes.