I recently ran across a fellow magician's post regarding timing his ceremonies. His belief is that no matter how long the ceremony takes, it is when the ceremony begins that is most important. Some how in his mind he thinks that the influences at a given time are locked into place by the start of ones ceremony.
I have to disagree here.
When you start the working matters less than when it is completed. Take for instance a birth of a baby. Without going into the mechanisms as to why certain astrological positions imparts their influence upon a person, we collectively understand that it is the moment of birth that defines which stellar influences have been inherited. A person can theoretically be seen as a talisman, and a talisman can also be a birthing of a physical body of sorts.
In the realm of magical timing, there are two major routes a would-be magician travels.
There is timing via planetary correspondences with the days and hours of the week, and then there is timing via astrological positions in the heavens. Both are fine and depend on the particular working a magician is planning to do, but which ever one chooses to use, the ceremony must be accomplished within the set time.
Now it is relatively easy to perform and complete a ceremony during one on the magical-hours of the week. But when it comes to basing a ceremony on the astrological positions, you normally only have 15 minutes. Its a lot harder to complete a task magically in 15 minutes especially to complete a talisman.
So the trick is to make most of the talisman during a magic-hour and day that corresponds to the ceremony before the plotted astrological time. Then at the moment of the astrological event, you put the final touches on the talisman and invoke the entities to inhabit it.