VickieM, I would start the jaw exercises now and continue until you get the desired result. With regard to the HBO, I did the 30 with no problems, and even had fun. It is common to give meds for anxiety prior to HBO treatment so be sure to arrange that in advance. Remember that there is always someone right there so he will be able to communicate all the time if he needs to. Watching movies or television makes the time pass quickly, and sometimes I slept. He will do okay! It is fear of the unknown that is the worst, so after the first one, he will be able to relax.