Hi - don't forget you start the day count from when eggs have reached the correct temperature so generally add on a day to the timings. Plus the larger the egg the longer it will take to hatch, plus very old or very new eggs will take longer also.
I always give my Marans eggs 3 or 4 days grace just to be on the safe side.
I often don't bother to take them out of the rocker until the first one begins to cheep or pip, and I don't think it makes much difference. Early chicks will often hatch in the rocker, climb out and fall to the bottom and still be fine.
Relax and enjoy, and if, heavens forfend, any don't hatch, then just think that they wouldn't have done anyway
The majority of egg deaths are caused in the first few days of incubation anyway - its just the stress of hatching brings these problems to a crisis.
All the best
Sue