I have a complete placenta previa which I was diagnosed with at 15 weeks. I had an ultrasound at 23 weeks and it was still complete. I go in for another at 29 weeks. If it is still complete, I will have to plan for a c-section. Because I had 2 bleeding episodes, I've been told to take it easy, not lift anything over 5 lbs, and pelvic rest.
Most previas do move before delivery. If it doesn't they plan a c-section. Some people have bleeding episodes, and some people can go through their entire pregnancy without one.
Good luck! fx that it moves for you!