I hope I ask this correctly. I understand that it's not good to hatch out eggs from a hen that just starts laying. I've heard to wait until the eggs are 50 gram or the usual weight for the breed of the hen.
What's your experience? How long do you wait until you hatch out eggs from a new hen?
What are your goals. What do you expect from the chicks that you hatch? Some people don't hatch eggs until the chickens are two years old or so. They want to see what the chickens will look like and what traits they have before they hatch eggs. Maybe they are breeding for show or to maintain the breed according to the SOP. If they are breeding for egg laying they may wait until the egg laying season is over before deciding which hens' eggs to hatch. Some may just wait until they know what color of egg the pullet will lay. And so on and so on. There are all kinds of different reasons to decide when to hatch eggs.
When a pullet starts to lay you can sometimes get some pretty weird eggs: thin shelled, no shelled, double yolked, no yolk, or some other weird egg. These eggs are unlikely to hatch a healthy chick. As complicated as the internal egg making process is I think it is amazing how many get it right to start with.
I've hatched pullet eggs. Sometimes the hatch rate is pretty good, sometimes not. An example. One time I put 5 eggs from one pullet and 6 from another in the incubator with other eggs. Both pullets had just started laying. I got 5 out or 5 chicks from one pullet's eggs, 0 out of 6 from the other. I don't know why, maybe the rooster had not noticed the pullet's egg needed to be fertilized. Overall my hatch rate is not as good as with full sized eggs but it usually isn't that horrible.
Pullet eggs are small so the chicks that hatch from those eggs are small. Most of the chicks that hatch from the small pullet eggs do fine but my survival rate isn't quite as high as the other chicks. Still, it isn't horrible.
I find that if I wait until the pullet has been laying a month before I set her eggs these problems mostly go away. If I'm cranking up the incubator anyway and have some available I'll toss them in. But if my major effort is the pullet eggs I try to wait a month at least.