> 2) Even if you lived there and devoted your entire days to study, it would be difficult to ramp up that quickly.
These are 2 wildly different scenarios. If you stay with a family, immerse yourself and go to class every day you would have an advantage over an FSO officer.
As to not being professionally fluent in that time, that is definitely true. But you should reach a level where you can be independent enough to get around, speak and understand.