Your joy is contagious, thanks for sharing your good news with us. I LOVE the idea of a song for the baby.
I always sang made-up songs for my kids, and I sang them with gusto, even though I'm not too great at carrying a tune. I figured they wouldn't complain, and they didn't. At least not until they were teens. And then of course, we went through that inevitable period when nothing I did was right.
Anyway, I still remember the special song I made up for my son. It was sung to the tune of "Guinevere" from Camelot. The refrain went, "Zachary, Zachary, To the rescue, Zachary..." I sang it whenever he needed calming or to have his fears eased. I found it really was effective.
Though not something I had ever been taught in any of my collegiate child development classes. LOL!