So here's an interesting one. I can't even begin to identify it and it has some odd characteristics.
The movement is a 21 jewel 6AK with a very clear omega data code. The case is marked "Bulova Fifth Ave New York. It's 10 K yellow gold filled.
My guess is 1940 for both the movement and the case but that's outside of the listed date range for the movement. I've had no luck so far with the ads.
All other 6AKs in the database start at 1947, so this is by far the earliest 21J 6AK movement we have seen.
Can you confirm that it has a single diamond at either end?
I looked thru both the Catalog and forums and could not find a match. I'm stumped.
I think this is a Dolly Madison. There is one very similar in the 1939 sales book. The Dolly Madisons had 21 jewel movements. I will look more tomorrow.
I also agree that it is likely from the Dolly Madison series.
The Dolly Madison "K" looks close.

It looks really close to the "K".
It appears by the ads that the dial didn't change the variant. This is a close up of the "K" from the 1939 sales book. It has a different dial to the ad above. After looking at the details it is close but not an exact match imo.

I'd say the Dolly K
Following the crowd - 1940 Bulova Dolly Madison K
Hi, guys.
I'm sorry to be getting back to this conversation late. Here is a close up on the end piece over the lugs.

I certainly agree that it is extremely close. The swirls on the side are the same and it does have a central diamond. But that border around the diamond looks different.
[shrug] It's up to you guys. I'd say likely a Dolly Madison. If it were me, I think I'd hold off on the "K".
In reply to Hi, guys. I'm sorry to be… by tshanno
I also agree it is likely from the Dolly Madison series.
Closeup of lug does show it is a different design from the ad. Subject watch shows an engraved edge raised "teardrop" shape while ads do not..
Tentative 1940 Dolly Madison - no variant for now (for me).