You can start in either bottom corner(depending on whether you are left or right handed) and work across. When you roll up go back to same corner and work across. Some believe you should start in the bottom middle and work toward edges. I guess you will just have to do trial and error to see what works best for you. When quilting crosshatching make sure all lines are quilted in same direction to avoid puckering. On the cross hatching you can quilt, for instance, north west for about 10 inches or as far as you can reach and then quilt southwest on the next diagonal line. It's a little hard to explain without a diagram but just think of quilting a triangle. In this example all lines going northwest are quilted in the same direction and all lines going in the other direction are going the same way. Or you can quilt all lines away from you, when you have quilted as far as you can reach, leave needle in quilt, quilt next line, etc. Roll quilt and then pick up your needles and continue on.
This is a lovely pattern and you did an excellent job of marking. I have an older Z44 that I just recently got out of storage. I didn't use it because I couldn't get the hang of quilting away from myself with my thumb. However, I got a bug a couple months ago to give it another try. So, I am now the owner of a new thumb thimble and have my pattern on paper, which is a wholecloth as well. As soon as I complete the project that I'm working on now (hopefully, in a couple months -- I've been working on it 2-1/2 years) I'm going to give it another try.
Keep us posted on how your are doing.