Thanks to multiple reprints, many modern astrologers are acquainted with the works of W.J. Simmonite. However, those reprints of his horary work have been based on the 6th Edition, which was published posthumously in 1896, with commentary (and some changes) by John Story. The text here is quoted from the 1st Edition, pp 55-56.
Of the time of erecting a horary figure
W. J. Simmonite
219. 1. Many disputes have arisen about the proper time for the figure of a horary question to be erected. Some think, the moment when the querent is first seen by the artist; others, when he salutes him; others, when he inquires of him, &c. But the proper time is the hour and minute when the querent feels the most anxious about the matter
2. If a person apply to an Astrologer, the figure must be erected for the minute the querent proposes his question.
3. If a letter be sent to an artist, the time of the letter being received is not to be taken notice of, but the moment the artist reads the very question.
4. In sickness, the time must be taken when the person first spoke to the physician concerning the disease, whether the querent is the afflicted party or not.
5. If a parent bring the water of a child, though the child cannot speak, the 1st house represents the child, and not the 5th, and so of the rest.
6. If it be not a question, but a sudden event, take the moment of its commencement; as the setting off on a journey, beginning a letter or any business, &c., or when you first discover the loss of any article: in all these cases, the first impression on your mind is the time and moment for the figure