This sounds like your first time. Use it as a learning experience and try to follow the usual recommendations, especially the ones that should have come with your incubator. Observe your humidity. Watch how long it takes from pip to zip and how long it takes them to dry off once they hatch. See how long it takes for the hatch to be complete, from the first one to the last. Notice if they are hatching early or late. If you set them on a Monday they should hatch that same time of day on a Monday. Hatching is a process where they pip, they rest, they zip, they eventually kick off the shell, they rest, then move around, eventually they dry off. If they are more than a day early or a day late, you probably should adjust your temperature a half a degree or so next time. Odds are things will go pretty well this hatch, but you might see something that needs to be tweeked next time.
Once they start hatching you will probably see the humidity go up enough and stay high enough to worry you. That is normal and natural. 65% was plenty high enough for my first one to hatch, and once they started, my humidity in my 1588, not the
Brinsea, quickly jumped up to 85% and stayed there. Don't open it, not your first hatch. Get some experience doing it the way you are supposed to before you start experimenting. And do an eggtopsy on the unhatched eggs afterwards.
Chicks are put in boxes and mailed out from hatcheries the day they hatch. They arrive alive and well 2 and often 3 days later. Mama hens will keep their chicks in the nest from when the first one hatches until the last one dries off in a normal hatch. You have at least 48 hours and probaly more after the first one hatches before you need to open the incubator. Expect the chicks to knock the unhatched eggs all over the place. Don't be surprised to see a chick laying with its head in a half egg shell, wet and stretched out and looking like it is dead. It is not dead, it is just resting.
I'm not saying everything will go perfect for you the first hatch. Mine certainly did not but I had 17 out of 27 hatch with 4 clears. Since I went with the basic standard recommendations, I know what I will adjust next time to try to improve my next hatch.
Good luck with your hatch. I really hope it goes well. And I know it is exciting and stressful. You can manage.