Presidentially the Southern Strategy worked almost immediately, reversed only by candidates native to the South (Carter, and Clinton partly because of Perot). With Congress it took longer because there are other factors there--incumbency and maps.
And as for "two pregnancies and then she'll get it"? Fuck you. How about teaching everyone how to have sex safely so that almost none of them get pregnant unintentionally? (Oh wait, that would mean that women could enjoy themselves and not be chained to a kid and actually have a career. Can't have that!)