It depends on whether you're quilting in a hoop or without a hoop, or in a frame.
When I quilt in a hoop or without one, I start in the center and quilt in a circular motion on my way to the outside.
I usually quilt in a frame, and in the frame I start in the center of the row, quilt toward the edge, then go back to the center and quilt to the other side. And because my frame has 3 poles, I start at the beginning of the quilt.
The theory is I don't want to quilt in any puckers. If I quilt this way, I smooth out the backing and top.
I hope this helps.
Janet