Birth it and machine quilt it in the manner in which you are most comfortable doing. SITD would be fine. I like the stability quilting gives it vs. tying when it comes to things that babies/kids use...as this will likely get washed a lot and will be loved for years to come! :-) Oh, and once you birth it and get it ready for sewing, if you stitch along the border where the purple-bluish color (I can't tell what color it is on my monitor) meets the other colors of the quilt...it will make that border have some emphasis and stabilize your quilt nicely. (But I would do it after you've done the other quilting.)