The appointed time of trumpets is one of the simplest appointed times which shows us when new moon day is. In Leviticus 23:23-25 it says:
23 Then Yahuwah spoke to Moses, saying,
24 “Speak to the children of Israel, saying: ‘In the seventh month, on the first day of the month, you shall have a sabbath-rest, a memorial of blowing of trumpets, a holy convocation.
25 You shall do no customary work on it; and you shall offer an offering made by fire to Yahuwah.’ ”
I am a very visual person. I like thinking about problems by seeing how it all goes together. A visual for me allows me to rule out the options very easily. I can quickly see what methods work and what methods do not.
Consider for a moment that you are driving along a track.
- The track has markings on it which you cannot see until you are right upon them.
- The track varies between 29 Kilometres long and 30 Kilometres long.
- You are told that you need to flash your headlights during the 1st Kilometer.
- You are told that the 1st Kilometer will be after either the 29th or the 30th Kilometer.
Now consider these two models:
MODEL 1: SEEING THE SIGN AFTER YOU PASS WHERE IT STARTS
EXAMPLE 1:
This model places the sign that we have reached the end of the track, after we have completed the distance required. That is, we do not know we have started the first kilometer until we reach the end of it. This might sound logical, until we actually test it to see how it works.
Below, the person approaches the start of the 29th Km. They may believe that this track only has 29KM so they start to flash their lights as they beleive they are in the 1st Kilometer now. But as the round the curve they see the sign which says 30KM. They have just flashed their headlights, but did not do it at the correct time.
Here is how this would play out:

This becomes even worse when you consider what happens when we assume there are 30KM on this track and arrive around the corner to discover that there is only 29KM.
EXAMPLE 2:
In the next example, the person believes that there are 30KM on this track. So as they pass the 29th KM, they do not yet start to flash their lights as this is to be done only during the first Kilometer. However as the round the curb, the sign is seen which tells them they have just reached the 1KM mark. The person has failed to flash their lights during the 1st Kilometer.
Here is how this would play out:

In both of these examples, the sign is seen after the event. The event is the first kilomter and the sign is at the end of the event. Seeing a sign after an event, does not tell the person when the event is.
In the first example, the assumption was made that it was the 1st Kilometer and the lights were flashed. It was discovered at the end of the trip that it was actually the 30th Kilometer. They flashed their lights too early.
In the second example, the assumption was made that it was the 30th Kilometre and the lights were not flashed. Instead, when they arrived at the end, they found that it was actually the 1st Kilometer. They flashed their lights to late.
MODEL 2: SEEING THE SIGN BEFORE YOU PASS WHERE IT STARTS
Yahuwah tells us that He gives us the luminaries to be used for signs. Consider what a sign is. A sign is something you see before an event. It is designed to warn. Seeing a sign after an event, as we have just seen in Model 1, makes the purpose of the sign null and void. The sign only tells you that the event has already been.
In the following example, the sign is seen before the event. The sign is a warning the that the 1st Kilometer is approaching. At the 29th or at the 30th Kilometer, a sign is seen right before the 1st Kilometer, telling the driver to flash his lights.
Here is how this would play out:

So why have we looked at this? Because it is important to understand what a sign is and when they are seen, with respect to His appointed times.
If you were to consider for a moment, the flashing headlights is actually the blowing of a trumpet. The sign is the sighting of the new moon upon the last evening of the month. Then the trumpets can be blown during the first day of the appointed time of trumpets.
There is no way to tell for certain if you are blowing the trumpet at the correct time, if you blow the trumpet before you see the sign.
The following video highlights this issue, with the command to blow the trumpets the evening before and the day of the appointed time of trumpets.