The typical time for a rotator cuff tear
to heal to the bone after surgery is 6 weeks.
That is why most people are in a sling for 6 weeks after surgery. It then can take 6 weeks to gain motion and another 6 weeks to gain strength. Recovery can take up to 6 months. Sleeping on your stomach is fine as soon as you are out of the sling and can do it comfortably. WilsonShoulder.com