Out of the 73 records I have 6 with the shield. One of those records has an engraved back for 1923, so I agree that shields are certainly later than the globe.
My obvservation is on a Hudson Maxim pocket watch with a case serial number of 1025261 that also has an engraved case with 1923.....this in itself doesn't mean the watch was manufactured in 1923, it could very well be 1922, or even 1921.
Placing the serial number of this watch in position with the 66 globe records, the position number is 36.
It is still somewhat of a guessing game which is why I'm building a list focused on case serial numbers.
My gut is saying 1922 based on when Bulova started to ramp up for their national advertising campaign of 1923.
BUT I certainly could be wrong and it could be 1921....I'm just seeing many more lower examples than this number that suggest it's later than 21, and it has Lady Maxim on the dial, others earlier examples do not.