Welcome! I've been learning for five months, and I'm not fluent by any means, but I can make some (very) basic conversational phrases (and, well, cuss people out :P). The time it takes to learn depends on your expience in learning languages (not a lot of us have this) and your personal dedication to the learning process. Sorry that I can't give you a more accurate estimate, but I predict that I will be fluent enough to say that I have "learned" the language in about seven months (a year in whole).

I believe that grammar should be learned first, because of how essential it is. However, when you first start, it could be good to learn some basic vocabulary and basic phrases while you are learning grammar.

Best of luck!