There are several errors (no offense) in your reasoning. First, Jesus did not say 'No man knows or will know the day or the hour' - what He said was true when He said it, but it does not necessarily follow that it must be true until He returns. Second, Jesus is very precise in saying 'day' and 'hour' - note that He does not include 'month' or 'year'; thus, someone might know within a few days (perhaps calendrical questions and variances would prevent them from 'knowing' the exact day)...