It’s a matter of preference as to where you start to stitch your project. I prefer the upper left hand corner, some prefer the middle. But, what is most important is the very First Stitch.
Start at a vertical thread. A vertical thread is the thread going north to south, over the horizontal thread running east and west. The vertical thread acts as a post and holds up the understitch resulting in a prettier stitch. Starting at a vertical thread also acts as an early warning. When a regular stitch suddenly begins at a horizontal thread, you know immediately that you have miscounted and you will find that somewhere you have stitched over three threads instead of two.