Tomcats showed up in -41, not -45 if i remember it correctly, it was just prior the attack at Pearl Harbor.
The point of the thread is to show the more unconventional designs. Most of them never made it to the squads but its fun to think about U.S Navy having the F-5U instead of the Corsair or Luftwaffe having the Do-335 as their front line fighter.
Most of these concepts wasn't bad at all but it wasn't the time to spend industrial resources on them (in case of the Allies) or there wasn't enough resources (Germany) to get them ready for war in time.