Help with humidity!

[LilBantams]

I started incubating my first batch of large eggs and bantam eggs (I have heard from that it is OK from some who have done it) last Thursday the 21st. I have the temp set at about 100. I filled the channels at the bottom all completely full and started the batch. When I started, I didn't have a hydrometer. I finally bought one a few days ago and I thought it was wrong because it was reading around 38-39, so I bought another one but it was reading the same thing! So I added a wet paper towel, but then the humidity dropped to 35. I'm so lost and need some advice. I have an older incubator. It's set up almost exactly like a Little Giant incubator but I'm pretty sure it's an off-brand. Also, the humidity where I live runs around 45-50. I don't know if that matters.
A question:
How long does the humidity take to catch back up after I open the incubator?

 

[Yorkshire Coop]

Your 38 - 39% humidity sounds fine and your eggs should lose enough moisture and the air cell grow adequately with that. When you candle you will be able to see if you need more humidity or less. Have you day 7 candled? Did your air cells look ok?

It can take a while for it ruse when you first add a water or cloth so you do need to give it time. When it comes to lockdown and you need at least 65% for hatch you can add more paper towel or sponges to create more surface area of water. It's the surface that creates the humidity and not the deapth of water.