Just for the record, the FM-2 is not an early-war fighter. The F4F-4 is, so are both P-40s. Even the Hurri IIC would be classified as mid-war. Likewise for the Ki-61.
I would define early war meaning in active squadron service prior to 1942.
Early-war based upon being in active service before 1942, would include:
P-40s
F4F-4
Bf 109E
Bf 109F
Spitfire I
Spitfire V
A6M2
C.202
Hurri Mk.I
Bf 110C
My regards,
Widewing