Yeah, in my experience it's never proven to be too difficult to get a table there. Two weeks in advance should be plenty of time unless there's some big event going on there the day of your visit.
IMO, I'd recommend Napa Rose at the Grand Californian over anything in the parks though. You'll get a much more satisfying meal for pretty similar $$$. But if you've never been to Blue Bayou before, it's definitely a unique experience that you should at least try once!