Everyone will say this is wrong. It probably is. I've prepped a couple dozen humidors, either for myself or when I build some for friends in my wood shop. I wipe the hell out of the inside with RO water on a paper towel, close, and set aside. A few hours later, repeat. Next day, repeat in the morning and evening. When that is absorbed on the third day, I put the cigars in.
I've always had them stay at the right humidity right after that.
It's wrong, yet works.