Well, please cool down first. Take a deep breath and think first how much it is going to cost you to involve a lawyer. Probably a lot more, if you find one. Every problem is specific, and it depends on the individuals involved. So, there is not rule that applies to everyone. I can tell you something that can help you make a calmed decision.
You are not alone in this. Several people have come to me requesting a guitar, and the strongest enphasis is over the delivery time (even more than over the quality itself). They have said that they had a bad experience with other luthiers on the promised delivery date. In my first years, I wanted to please and get customers so desperately, that I promised (to the best of my will) to finish the guitar in a certain time. Only to find out that it was hard to do it. Then I started extending the time, etc. Now, I have a grasp of the exact amount of time it would take me to finish one guitar, and even then, I apply a safety factor to it. I do not take more than what I can handle. Some luthiers may be taking more than what they handle.
There are other reasons a luthier may be late: Once the guitar is almost ready, he got sick or had a personal problem to deal with, he may have had an accident with the guitar that renders it impossible to deliver it to you. I agree that he should keep you posted at all times. That is the good thing about contracting a luthier, you are supposed to see the progress. Did you drive the 90 min to see him and verify the real reason for the delay?
If it was because your guitar got sold to another person, or because it requires to many details that he underestimated the amount of work? Is he too busy?
What does the agreement read? It will be ready AROUND November of by November 30? of what year?
I suggest you drive and talk to the guy. Walk around his shop, touch the other guitars. I once was late with a guitar, and to make sure the customer was happy at the end of the transaction, I replaced the back and sides from Indian rosewood with Brazilian rosewood. The customer was happy. In another ocassion, I had an accident with a guitar at the finishing stage, and I informed the customer, and again, I changed to BR. Good thing Ihave BR around. Dont be surprised if you find many people in the same boat you are!!
I make guitars not as a business, but as a labor of love, love to the guitar. By doing so, people come and come. So I do not offer or push it. If I am not happy or impressed with my customer, the relationship is not good, I am sure the guitar will also come that way. If the relationship is great, the guitar will be great.
I just got a commission for a flamenco guitar from a professional player, educated in Malaga, Spain, great great player. He tried several of my guitars and told me that my guitars were better than the guitars or two other famous makers (I will not mention the names, because I admire those luthiers - I know they make great guitars). Guess how I feel? GREAT, I have not taken a shower, I do not want that comment to go away from my skin!!!! or my ears!!! One thing I tell you, that guy is going to get the BEST guitar ever!!. So, it is important that you keep your cool and whatever the problem the luthier is, you go and talk things over.
Keep it cordial and you will enjoy the guitar when it comes. Otherwise, you will not be able to enjoy it. How much is the deposit by the way? $500? $1000?. Keep the amount in mind when making a decision. I hope it will work for you, and you get the guitar soon.