My wife and I notified her parents about our intention of getting married about a year earlier than we actually did.
We actually didn't go begging for their approval, it was more of a "I'm telling you first out of respect, but we're going forward with it anyways". There was few things they could do, my mother-in-law asked for us to be married here first, then do the ceremony in Spain, and we agreed (we had to do both, eventually, so the order didn't matter much for us). Plus, we had been living together for a while and they knew it, so in fact they were expecting us to get married.
Of course, we had met and been living abroad, and we have to came to Taiwan to live together, which was the opposite situation, but we also told them that at some point, our intention would be to go back to Spain, because both my wife and I think that living in Barcelona beats anywhere in Taiwan (although she had to work for a Taiwanese company to realize that).
"Roda el món i torna al Born!" - famous saying from Barcelona.