1950 was very unoptimized at 18 rounds, so I beat my record. 15, maybe 14 is possible. Before round 8 is just sending ships across an ocean and Zhukov hitting Cairo so I could then take Ankara then Kiev for Guderian and missiles.
After this there are two records I would like to beat or tie: 1939 no gens and 1939 1 Star. At 14 I had $2,000 (before I used paratroopers seen), so with better planning 14 is definitely possible. I gave you something to do while generals are upgrading Harry Lillis "Bing" Crosby Jr if you get 14 I might try 13, but that will certainly be challenging.
After doing 1943 in 11 rounds, I thought 10 to be possible with optimization. Turns out it is. This took around 3 hours as I did everything slowly and precisely. 10 rounds glitches the score or something as no bonus was given for rounds. I do not see 9 being possible, due to mobility constraints, but with missiles and good Africa luck it might be. The only room for improvement is not using rumor (I have it on Konev Guderian and Rommel), opting for plain or explosives instead. I also put Arnold on Tokyo and he only had 2 bombs, whereas in Bankok to take the Phillipines would save much more money. That or replace Arnold with Rokossovsky (which I do not have) for help in the Balkans.