Is this construction used correctly?
It was not until his becoming the manager that he got married.
Is this construction used correctly?
It was not until his becoming the manager that he got married.
I think technically it is OK to say this, but it would sound better if you wrote: "It was not until he became a manager that he got married."
"Becoming a manager" implies that the process of "becoming" is important (for example, learning what his new duties are).
In my opinion, that structure is correct but it could sound better if you say:
It was not until he became the manager that he got married.
If you say "becoming", you emphasise the process of becoming manager. Despite that I think you should state the sentence like it is a fact using infinitive after "It to be not until + subject".