Low Placenta and measuring ahead

I am 26 weeks and this is my first pregnancy. I am due May 26th but little man is measuring a week and a half ahead. I had my check up today and they did a sonogram and found that my placenta is low and next to the cervix. I guess if it doesn't move then it could result in a c section or a premature birth. Has anyone been through this and your placenta moved before hand? Thanks so much.