Sounds like you are ready to go! Wavy line quilting is a great choice, I use it a lot. I do make my first stitched wavy line down the center of the quilt, top to bottom edges, which helps stabilize the whole quilt together. Then I work adding lines from the middle alternating on both sides toward the outside edges. This way you should not have much issue with the layers shifting. Post a picture when you are done!