I'm guessing on the age here. This movement is early early. I picked up this watch because of the enamel. Bad news and good news... The case may not be Bulova as it's stamped 18K APEX. Good thing... 18K.
A very interesting watch. Given the signature on the movement, and the serial number, I would place it very early 1923. This was a time that American Standard did not produce enamel cases yet, so Bulova had to go somewhere else. Based on my research, I am almost certain that APEX was the one. It really must have been a try-out by Bulova. On Watchophilia is another one: https://www.watchophilia.com/photogallery/bulovas-1920-1929/a1924-unkno…. The try-out was probably not successful since so few are found. Only in 1928, Bulova would come with a wide range of enamel watches. Still not successful since most of them silently disappeared again in 1929.So for me, definitively a Bulova, albeit Unknown and from 1923.
So no date stamp on the movement? I imagine the earliest stamp would be an astrix (24), but would agree that it's more likely to be pre 24.
Regards the case, I wouldn't neccessarily discount it not being original, as we know Bulova used other 3rd party case companies to supply many of their solid gold and platinum cases.
Unknown for now.