This morning at around 6:30, I took the leap and plugged in my incubator, without any eggs in it. I poured warm distilled water into the grooves in the bottom of it and put the lid on, and the humidity immediately shot up to 75% and the window got all steamy. The booklet says ideal humidity tops out at about 60%, and warns that excess humidity will damage the circuitry and void the warranty. So, I dumped all the water, and decided to test the humidity without any water in it all.
When I returned at around 10:30, the humidity had dropped to around 30%. This time I poured about an ounce of room temperature water in and replaced the lid. An hour later the humidity was at 45% so I added a little more water. Now, at around noon I seem to have attained the ideal conditions for a lasting relationship. So now my plan is to get on more intimate terms with my incubator while collecting the best looking eggs from my hens for the next couple of days.