Hi Margarita, you do have to start at the bottom left or right, depending on which way your fans go. If you are right handed, you would start on the right side for hand quilting. They are are little fiddly to mark. If you believe Joe Cunningham in this, you won't worry too much about perfect straightness. In the US in the old days, they did this pattern because it was easy to quilt the curves, so they probably didn't mark much. I love this pattern!
Kathy