From Firefly production to squadron service

If Firefly first flew in December 1940 and production began at the end of 1941, is an October 1942 service debut realistic?

October 1942 is too late in this accelerated scenario; service could begin roughly three or four months after production starts.

The proposed timeline already moves Firefly development forward. Once production begins, operational introduction would follow within roughly three or four months instead of waiting until October 1942. This separates first-flight chronology from the final production-to-squadron interval.