If a MCU is packaged in a MBB, is it then necessary to put the MBB in a climate controlled cabinet in between usage? If what is the recommendation of when to put in, how many days, weeks or maybe months can be accepted before the need of a cabinet?

[TDK]

Unopened? From experience, months should be fine. But it ultimately depends on the environment.

Not sure what you mean by "in between usage". It sounds like you're opening the package.

See:

https://www.st.com/resource/en/application_note/an2639-soldering-recommendations-and-package-information-for-leadfree-ecopack-mcus-and-mpus-stmicroelectronics.pdf