Mt 24:35-36 "Heaven and earth will pass away, but my words will never pass away. But about THAT day or hour no one knows". But, yes we agree that we don't know EXACTLY when He returns, as He says in VS 42, but who is the "owner" in 43? Interesting, but yes either way "Son of Man will come at an hour when you do not expect him"
Either way Christ returns in Rev 19 and reigns for 1000 years in Rev 20 after which there is the final judgement and only then the New Jerusalem descends upon the New earth. So there's a distinction to be made between Christ's return and the date of the New earth.. (removal of the Old).