I agree totally. Stick with just the one and you will have a true blue friend. No telling what would happen if you add another. Like illusive said...they might not even like each other. It's happened to others time and time again.
I lucked out and my 2 get along great. I did wait til I had had my first, Levi, for around 8 mos or so before getting another. By then his bond with me was so strong it never changed.
Keep working with the one you have very very slowly. A solid foundation of trust is key to a tame and well balanced bird friend
Oh! Welcome to the forum and congrats on the new baby