If the man has asked and the woman has accepted, I do not see the need for any delay. Six months is, IMO, an arbitrary period with little to no support. If a man and woman have already courted for some period, however short or long, and desire to be wed, it does not take six months (or four, etc.) to ascertain their fitness and resolve. IMO, waiting for several months is asking for trouble -- especially during this era.
I do not believe that was the way of things in saner eras (among which I am NOT including how things were done in the 50s).
As for the plans, that, too, is more of a modern phenomenon. IMO, normal people did not invite guests from all over creation, nor arrange for mega-parties, etc.