Okay, it's not done. I still need to blanket stitch one side of the opening and block it and find buttons and sew them on. But it's sewn up! And since that took more than two hours to do (don't ask me whether or not that includes sewing the side of the sleeve to the side of the back plus picking them apart again) I felt it deserved a day all to itself.
Now that it's in one piece I think it might be a six month size - whew! - which still won't put it big enough for this baby to wear at Easter, but maybe that's just as well. Somebody might mistake him for a beautiful cuddly egg and try to put him in a basket for a table centerpiece or something.