Agree with what others have said. Also, make sure to start basting in center of quilt & work your way out. Think of quilt as being in 4 quadrants. Pin from middle out in A quadrant. Then repeat in the diagonal quadrant. Continue until it's all pin basted. Then you usually want to add a quick thread basted stitch along the edge of your quilt (less than 1/4" from edge -- some people don't remove as its hidden in binding, but I always remove it). This basting line to make sure the edge doesn't fold under & get caught in the quilting (ask me how I know).
I used about 425 in current quilt that's 68x68" and ideally I could've used another 25-50. I like the curved pins. They make the process go faster for me. Good luck!