A POD in early 1939 limits what can be done, but there are three things that would make a big difference. First give the BF-109 drop tanks, the Condor Legion used them in the Spanish CW. That would effectively double their operational time over England, making them more effective bomber escorts, and allowing them to engage in more free chase missions. Use the BF-110 as fast fighter bombers, to attack high value targets like radar sites, or aircraft plants. Never issue the order to suspend any project without a completion date of more then 18 months. The order assumed the war would be a short one. Considering Hitler planned on a war with the Soviet Union, and a long term showdown with the United States they should've figured WWII would last at least as long as WWI.