Whilst reading my Emily Post etiquette books, I routinely like to ponder why some traditions are not around anymore. Announcing that somebody just got engaged used to be a very formal affair. Days before the formal "announcement" the Bride and Groom wrote to their intimate friends and relatives telling them of said engagement and to not tell anyone else until a specified date. Upon completing that task, these intimate friends and relative entertained the Bride and Groom privately.
The formal announcement would have been made by the parents. This is done intimately by note, word of mouth and in the local newspaper or social register. Telephoning the Society Editor was a given. If you were a prominent citizen, then they would post your photographs. Engraved announcements were not correct and never done. If permitted, this would be our modern Save the Date as we know it today.