DEAR MISS MANNERS: Your mom mails you a birthday card. She has no way of knowing if the card arrived the day before, the day of, or the day after your birthday. (She is not the mailman.)
She assumes it arrived before or on the day of your birthday. Is she obligated to call you on your birthday, or by virtue of her sending the card, are you now obligated to call and thank her instead?
Basically, it's "I sent the card, so now he needs to call me so I can wish him a happy birthday."
And if you don't call them to say, "Remember it's my birthday" they get miffed.
GENTLE READER: Then call them. ("Them"? How many mothers do you have?)
You cannot seriously expect Miss Manners to come up with a rule about the timing of irascible courtesies. And even if she did, someone who is looking for an insult while in the very act of conferring good wishes is not likely to be satisfied.
A more relevant rule is: If you can placate a difficult relative with a trivial concession, do so.