I'd like to officially put this forward to the myBulova.com community at large to scrutinize and see if it holds true. We've always had a problem dating the very early 1920s vintage Bulova wstches and often used the first number in the case serial number to date the year of production.
Well I'd like to suggest that for pre 1924 watches (pre movement date code) we use the second number to date the year of production.
In studying a good number of pre 1924 models we have in the database I find the common component of the case serial number having a second digit beginning with either '0 1 2 3', thus corresponding to the years 1920,21,22,23.
Further we have examples of watches that have the first two digits of the case serial number '13.....' and the corresponding movement stamp of 'Bulova Watch Co.' rather than the pre 1923 movement stamp of 'Bulova W Co.'
I'm asking the community to put this to the test and examine all watches with a serial number beginning with a '1' and of course being pre 1924.
There are some exceptions to this but they are all sold gold cases and it looks like these had a different serial number pattern yet to identified. As always thoughts and comments welcome.... Just be gentle :-)