I do not think so. I think the days were said correctly but these ladies have tendency to give birth before due date. It goes by the way in genes, me and my sisters have the same, I have two sisters and of 11 of our babies only one waited till due date, all others were premature but fully developed. My obstetrician told me this predilection is hereditary.
Yes, does seem so. E.g. the king was missing Carl Philip's birth and they were so sure, Madeleine would attend the wedding of her brother, that I can't believe Nicolas due date had been mid of June.
But of course with a due date at the shift of months, Royals will choose the later month for the announcement.
And this pregnancy got 2.5 weeks after the one of Estelle announced (August 17 vs. September 4)
My guess is this baby is getting born between February 24 and March 1