Well, the exact wording of the verse is this:
But of that day and hour knows no man, no, not the angels of heaven, but my Father only. Matthew 24:36
Technically, only the day and hour are unknowable, we are told. Might we know the month or week? I have no idea.
Now, to this point in time, every other prediction has failed. This one might, also. It's always best to use discernment in these things.
If the date passes, then obviously it was not from God. Personally, I read things like this and reserve judgment. I would not hold this up as the primary reason for thinking time is short. Even if he was correct, we won't know he got it right until we're on our way up. (Or just a short time before, perhaps? After all, "no man knows" was in the present tense when it was spoken.)