Not as long as I thought I would. Just a couple of days to adjust the straps and pressure and I was good to go. Still a pain to have to put it on, but I seem to actually drift off faster with it on than I did without it.
Are you using a mask?
Yep. Covers nose and mouth. I have BAD apnea and need a lot of pressure.
Did you see improvements quickly?
Almost immediately. According to my Watch I now sleep soundly - no more mysterious "waking" activity. My heart rate is lower at night. I wake up more refreshed. I used to hit a "wall" at 3:00pm everyday, where I just really wanted to take a nap. No more. I still have energy at the end of the workday and if I have to work late, I still get home feeling awake.
What app do you use to monitor your sleep?