Now, I realize that I speak with a maternal bias, but seriously,
Simplicity 4711, alas now OOP. This copy was a generous gift from Amber. Thank you so much!! It is a lovely pattern and I really enjoyed sewing it up. For my average sized 8 month old, I sewed a size small, which is pretty much perfect. (Simplicity seems to think this is a 3-6 month size, but Duncan wears a 12 month in RTW. Be warned.) I did use a 3/8 seam allowance at the waistline seam to give me an extra 1/2 inch of length. I think it would have fit fine without, but the extra wiggle room is nice.