I understand your concerns about having surgery, but I'm afraid I can't really say whether it's too soon or not. If your joints have significant damage and you will eventually have to have surgery anyway, it may be better to go ahead and have it rather than continuing to suffer for several more years. On the other hand, if the orthopaedic surgeon thinks there is something that can be done that will keep you comfortable and help your jaw to function better, it might be worth waiting for awhile.
The best thing I can suggest is to ask lots of questions and be sure you understand exactly what condition your joints are in now, what kind of surgery they want to do, and what you can expect following surgery – both short term and long term. Also don't hesitate to ask for a second opinion. It's always best to have at least two opinions before considering any kind of surgery. Don't let the doctor intimidate you or walk out without answering all of your questions. You are paying him to provide a service and you have the right to have your questions answered satisfactorily.
Good luck to you!