Rav Shmuel Felder, posek at BMG, writes in his sefer that one is allowed to fill in the name he plans on giving on the hospital forms. (He says that we just don't call the baby by that name, but there is no reason not to write them on the forms.)
In Monmouth Hospital, they tell you that it can take 16 weeks for the social security card to arrive in the mail. I've always received it in a week or two.