I hate to say it, but that's most likely not going to be accurate. When you check your hygrometer at 11:30, it should read 75%. If it doesn't, make a note somewhere on the unit of how off it is since you probably can't calibrate that (if you can, dial it back to 75% as quick as you can after you remove it from the bag). I prefer the hygrometers that look like a little dial, they can be easily adjusted, then I don't have to remember how off the digital ones are to work out the correct humidity.
I've gotten some good hygrometers in the reptile section of the pet store. My Accurite thermometer/hygrometer combo is inaccurate on both temp and humidity, its usable as long as I remember to -4 when I look at it
relax mate its just humidity. Get the temperature correct and start the eggs with no water. The sensors could take a little while to stabilize. If you brought it in from the cold then humidity will be high until the internals warm up. You have a few days to play with the humidity sensors the eggs will be fine as long as the temp is correct.
Yep run your incubator dry, get it up to temp, open the vents to let it dry faster. Don't set the eggs unless your sure the temp is good. I prefer to dry hatch, keep an eye on the air cells and if they are growing to much add some humidity