If you smoke, you will be advised to quit because that will help so much. If the ashtrays you mentioned are someone else's, they need to begin smoking outside now.

Would it be possible for your sleep study date to be moved up? It can't hurt to ask. They might get a cancellation. Or, could you have it done someplace else?

What helped me was to sleep on my side while 'hugging' a pillow. The pillow helped keep my arm/shoulder from shifting toward my neck and adding weight and pressure to my airway.

The fatigue is really awful, but the good news is that it goes away soon once you begin using the CPAP.