UPDATE:
Still no peeps or pips from anyone yet. It's day 20 and the temperature changed again last night, but it wasn't as low and my dad was able to catch it early. And like you all said, things will be fine with a temperature change. I haven't candled in fear of disrupting one, so I don't really have a clue if I've hurt them or not with letting the temperature slip. All I can do now is wait and not touch anything, which I can do.
Though I am starting to worry a little because no one has made any noise. I've been peeping at them every day since I set them, as crazy as that sounds ^w^

But I really do love birds, ahaha... I feel like I shouldn't expect any pips yet, but I'll definitely let you guys know if no one pips tomorrow. I thought I saw something this morning, but I was using my phone's flashlight to look into the incubator, so it cast a shadow on a bump. It wasn't a pip, though. Hmm.
Anyways, thank you guys for all of your help! <3 I hope you'll follow me on my hatching journey as a first time chicken mom! I'll update as things progress. ^w^)/