99 is a touch low and 60-70 might be a touch high, with your temp steady at 99 it will hatch a bit late in all likelihood. Optimal temp is 99.5-100.5, hatch humidity should be 55%-65%. Incubation humidity in the 40s (42-48% ideally). Fluctuations will occur for all of us, it's especially tough here in arid CO to keep humidity stable, but when you think of how a hen hatches, temps and humidity will change when she gets off the nest to move about each day, even if only a few minutes. Don't candle, just put your ear close and listen to see if you hear peeping - not that this is a certainty, I've had them peep at hatch time and not even pip; if they can't pip they generally have a poor chance of survival and there isn't much you can do to change it. If you can hear peeping it still has a chance to hatch. Don't give up until day 25. Every hatch is a learning experience. In the perfect world every egg would hatch a healthy chick, and 9 of 10 would be pullets, but that isn't the world we have, and some chicks will develop right up to lockdown and quit.
If I had to guess, I'd say you will see a pip tomorrow.
