I am little bit confused here.
If you are on dependent permit then your permit should be renewed along with your spouse. It should not be considered indenpendent unless you wish you go for an independent permit.
if not then there should not be any constraint that you need to learn German within 6 months of your arrival. As far I know this is not normal scenario.
Also I am not aware of anyone getting a 1 year B Permit on arrival. It is usualy L Permit for 2 years and then it gets converted to B Permit.
As everyone suggested, I would suggest to clarify with your geminde
good luck