When is the serial number engraved to case?

[mjolnir2thor]

Hello fellow watch geeks!

I spent some time on the forum's search function this morning and was unable to locate information pertaining to when Rolex applied the serial number on pre-1970 cases. Does anyone know at what point the serial number (and model number) is applied to the case during the the manufacturing process?

I've read online that the case may be manufactured during a specific quarter (e.g., II 67) and due to the manufacturing process, parts turn over (1963: 1530 switch over to 1520 movement), supply chain delays, etc. watch completion may be months later. I thought I read that it took a full year to make a timepiece which may vary depending on the complexity of the watch.

Article Reference: A Note About Dating - Hodinkee (scroll down about to the middle of the article)

https://www.hodinkee.com/articles/ro...ference-points

Given my manufacturing experience, I would think the application of the serial number and model would be engraved on the case just prior of installing the movement. The engraving would not be performed unless the movement's assembly and testing completes/passes as to not waste the case. What do you guys think?

Any information my fellow watch enthusiasts provide would be appreciated!