The day formula stored for this lot is Ascendant plus Saturn minus the Sun. It is a plain construction with no lot inside it, so there is no cancellation to find and no doubled Ascendant to warn about.
The motion is almost exactly the Ascendant's, slowed very slightly. Saturn adds about two minutes of arc a day and the Sun subtracts about 59, so the lot travels about 359 degrees a day against the Ascendant's 360. In practice it advances one degree every four minutes, and a birth time in doubt by an hour leaves the sign in doubt.
The interesting feature is which planet does which job. Saturn is the classical significator of the father and it is the added term, while the Sun, which in the Hellenistic scheme is the day-sect significator of the father, is the subtracted one. The lot is therefore built out of the arc from the Sun to Saturn, projected from the horizon: the distance between the two bodies that both stand for the father in different parts of the doctrine.
Because both of those bodies are also sect-sensitive, the night formula reverses them and the lot becomes the arc from Saturn to the Sun instead, which places it on the opposite side of the Ascendant by the same amount. For a chart cast near dawn or dusk, where the sect is genuinely in question, the two answers can be a long way apart and the sect determination has to be settled before the lot is reported at all.