Whatever is required to fit in with other circuit traffic. Might be over the threshold or even a bit down the runway, most common is about half to a full mile final, might be more if required.
Sometimes it's no problem to overshoot the centerline a bit, or even desired. Sometimes it's a big no-no because of other traffic flying an opposite circuit to the same or a parallel runway.
What's probably also important to consider is the altitude you're at when turning final. On a one-mile final, being at 700 feet is slightly high but still perfectly doable. Fly a threshold base at 700 feet and you can generally start planning on a go-around.