If you draw the grid, you can embroider from anywhere. The easy way to find the center point is to fold the embroidery cloth in half, and then fold again where the two lines intersect is the center point. Also, on the embroidery chart you look carefully, there are small △ marks in the middle of the top, bottom, left and right, find the two small triangles extending towards the center and intersecting, that is the center point.

I'm rambling a bit, I don't know if you get it.