The Attribution of the planets to the days is encountered in the Græco-Egyptian papyri...as well as the much later grimoires, and is likely of Chaldean origin, as is the seven day week. The planetary hours schema is an adaption of Egyptian ideas encountered at around the same time. As well as coming together at the dawn of the Western magical tradition the planetary days and the planetary hours are also mathematically inseparable." -Jake Stratton-Kent, The True Grimoire (Encyclopedia Goetica Book 1)
The Magical Treatise of Solomon or Hygromanteia
The Auspicious Timing Calendar is built from many sources. One of the primary sources is the framework for timing presented in The Magical Treatise of Solomon or Hygromanteia1. I was first introduced to this in Gordon White's Sigils course, presented at Rune Soup (for $10/month you get access to the classes and lots of bonus material; its one of the best values going in occult internet learning), but if I fail to mention the additional work and ongoing efforts of Ivy from Circle Thrice, I would be being horribly remiss as it was her ongoing work that inspired me to create the calendar. Subscribe to her newsletter for a free copy of her Agile Magic Manifesto.
Hygromanteia is a magical text variously dated from 13th-15th centuries, that appears in multiple versions. In the most complete ones, it is a text primarily focused on the creation of parchment talismans, so it contains directions for making all the required implements (the parchment, inks, pens, etc) but also an elaborate system of timing that includes the Lunar Days, Planetary Days and Hours, specific prayers for controlling the planets and a group of angels and demons that govern the days and hours. There are other parts to the manuscripts, including spirit evocations and bindings, divination, a classical invisibility spell or two, but the largest part of the manuscript is about practical enchantment.
So what is practical enchantment? Quite simply, it's about getting things done. Its not, as it might seem, as simple as it sounds (it never is, is it?). Magic is an art and a science, it works best with finesse rather than brute force. That means knowing exactly what you are going for and having some idea of the exact right stone to move to cause the landslide. That's not the best analogy, but I think you can get the picture. Knowing where to apply the pressure, the least amount of pressure, to get things moving in the right direction and then letting inertia do the rest.
"Furthermore, if thou wishest to converse with Spirits it should be especially on the day of Mercury and in his hour, and let the Moon be in an Airy Sign, as well as the Sun." - The Key of Solomon
One can easily see why Wizard White adapted Hygromanteia for his sigil work: sigils are the most current epitome of practical enchantment and Hygromanteia is the oldest and most complete extant text on the subject. Sure, there are bits and pieces in the PGM (Hygromanteia is clearly descended from those works, just compare the it with Leiden Papyrus), but we have here one of the most complete systems in any grimoire.
Sigils themselves are clearly a modern adaptation of talismans. But they are not the only method available for practical enchantment. The modern magician has any number of methods available to them, it just comes down to aesthetics. Magic is an art. Find the method of practical enchantment that works for you: ritual oratory, spirit evocation (though this does tend to have its own peculiar timing elements), making talismans or icons, some form of conjure...magic is an art: it is creative, it is performative, it is arts and crafts; it is memory....