Caley, is the flooring carpet where you're laying the sandwich on? If not, then you can tape the backing to the floor, then put your batting and top and pin. How I do grid pattern quilting is I start at corner, sew to the opposite diagonal corner, cut my threads, then move over whatever distance and head back the way I came. I hope I'm explaining this good enough to understand, but in other words, alternating directions, I'll finish the one side then start on the remaining half. I do a diagonal grid both ways. I rarely do a grid pattern though, since I can FMQ faster than I can do the grid pattern.