Baby shower etiquette question

SBT1977

When I was getting married, several told me the proper etiquette is to wait until after the marriage to write thank you notes for shower gifts. Is this true for baby shower gifts as well? Are you "supposed" to wait until after the baby is born to write thank you notes? Obviously, I know I can write them any time -- and I'm leaning toward writing them immediately, especially since my shower is almost 2 months before my due date. Do people typically wait? I can't remember...