re: Matthew 24:36,37 "But concerning that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father only. For as were the days of Noah, so will be the coming of the Son of Man.
I've lost most of my notes on this passage (they were on VHS tape!), but there are some interesting discussions about this event, including these links I found while checking my memory: //www.wholebible.com/trumpets.htm & //www.messianic.ws/feasts.htm#H4.
When you look at the Jewish holidays (high holy days), all of them begin in the middle of the month, except for Rosh Hashanah, the Feast of Trumpets, which starts at the beginning of the month. A month is considered to have started when at least two reliable witnesses report to the high priest that they have observed the first sliver of the new moon, which can be a 3.5 day variance from the expected timing. As a result, Rosh Hashanah is sometimes referred to as the day which only the Father knows. Everyone who is paying attention knows the approximate time, or season, but not the exact moment.
As the passage above in Matthew indicates, we don't know the exact moment of Jesus' return, but as believers, we should know the season by the events that are occurring.
As for the 'catching away of the saints', that is a whole discussion in itself (pre, mid, or post-tribulation, and pre-wrath - the seven bowls of unpleasantness), including the possibility of multiple 'catching away' events. I find the above 3.5 day variance in the expected versus actual start of the holiday interesting, especially given the number of '3.5' events described in Revelations (the two witnesses are dead for 3.5 days, major events occur half way through the 7 year tribulation, etc).
A related discussion is the description of John measuring the temple, where he is not supposed to measure the outer courts. If you look at the temple mount in Jerusalem, It's possible to build a new temple, opposite the dome of the rock, with the dome of the rock occupying the space where the outer court should be. This is actually appropriate as the outer court was for the gentiles. One line of thought believes the tribulation will begin when the cornerstone is laid for the new Jewish temple.
Another related side discussion, the period between the start of Rosh Hashanah, and the end of Yom Kippur, is 10 calendar days, with the first and last day of the '8 day' event being 48 hours in duration. This can throw a wrench in trying to calculate when events are supposed to happen, but does support a 7 year period between the trumpets and atonement events. I also know that trumpets are blown at specific times during Rosh Hashanah, but I can't find my notes as to how many, or when they are blown.