How long does it take a manga to be translated?

Fan-translation groups can have a manga chapter translated from a range of the day it's released in the original language or up to a month after. It all depends on the skill, devotion and number of people they have working on a single project at any given time.

If you want officialy translated stuff, (which might be better or worse than the online scanlations you can find) I would have no idea.