I’d give you drying times, but they’re sort of meaningless, since it depends on the variety, the thickness of the fruit, the ambient temperature, and how you plan to store them. What I can tell you is that you’ll get happier results if you leave the fruit in large pieces, even if it increases the drying time to 24–36 hours. The pears were pared, cored, and cut lengthwise into four pieces; same goes for the peaches; the plums were just cut in half. In any case, I wouldn’t go any thinner than 3/8″.
Visual cues may be more helpful.
This is what the plums looked like raw:
(Bonus: note changing light quality in afternoon vs. morning!)
The plums are done when they look like prunes. Both the pears and the peaches should be flexible, but not moist. Pop them in jars, label them, and hide them well.