according to Jochen Priens "History of JG53, Vol.1" at least JG53 received its first Bf109E-7s in October 1940.
And that the JG53 used 300liter Droptanks first in November 1940 in combat action.
Seeing that the Italians are modelled in SoW:BoB - who also apperead very late , end of October was their first combat mission
http://surfcity.kund.dalnet.se/falco_bob.htm - a Bf109E-7 would fit in the timeframe !
BUT, my guess is , we will not see so much variants of one plane anymore - as in the IL2 series.
i expect ONE Bf109E version in SoW:BoB.
if it will be a -4 or -3 (only depends wich kind of MG-FF Maddox will choose) , i don't know.
and i expect also the -/B armament option (bombs) - to simulate the fighterbomber raids.