Sure, I could guess, but what if I’m wrong? The system will automatically adjust based upon my first guess. It will recalculate based upon weather patterns and will water as appropriate. But it will still be based upon my first guess. The calculation of how quickly the soil dries is different than the amount of moisture present to begin with. Garbage in, garbage out.
Perhaps you could provide a qualitative definition of soil moisture. I suppose zero percent is bone dry. What is 100 percent? Is that where one drop more would puddle on the surface?