Head down

Dominique • Myles John 3/8/16. Micah Robert 6/29/17 baby girl due 10/8/20
I've been reading and trying to see when the head down process normally takes place. From what I've read is 28-32 weeks. 
My babies head has been down since 25 weeks. Is that normal or mean anything? I am  measuring 1/2 weeks ahead, could that be why?