Rescued lab mix

Question
3 weeks ago, I adopted a one-yr old yellow lab mix ( ? pitbull X).  She received no training from her prior owner and is VERY mouthy.  I notice that most mouthing q's center around puppies.  I am doing the "turn and shun" after offering a toy instead of my hand, foot, elbow, etc. has been rejected. She begins basic obedience in October and has already had a 1:1 with a private trainer.  Is there anything I'm not doing that would be helpful?

Answer
The main difference between a 7 week old and a year old one is that the bad habit is even more ingrained in the older one and will take even more work to correct.  Just repeat another thousand times.  

I am glad you are giving the dog a chance of a life.  Yes, rescue dogs can be a lot of work, but we need more people like you.