I will probably hatch 300 to 400 chicks this year. I have a 1202 incubator. Once my birds start laying I will put eggs in every 4th or 5th day all from different breeding pens. All the eggs are marked with pencil, I never use a black marker. I read somewhere that the marker can seep into the egg. That can affect your hatchability. On the 20th day I put the eggs in the bottom of my incubator in egg cartons and mesh bags. When chicks hatch I mark them with a colored marker for each different breeding. One breeding will have one blue stripe on his head, another 2 blue stripes, one red stripe, two red stripes, one blue stripe and one red stripe etc.etc. After about a week or two I wing band my birds. This gives me a chance to go over them again. The colors I have to be careful with are blue and green. Once I waited to long to wing band and I really had a tough time distinguishing between the blue and he green. My own fault. I have a 5 tier brooder and I mainly just use the top three tiers. I could have 30 to 40 chicks in my top tier, while I'm after I wing band I move them to the second tier. As more chicks hatch I will keep moving them down to the third tier. This gives me a chance to look the birds over again. The main thing in all this process is keeping good records. This is key. By wing banding I know which breeding pen they came from. When I put them outside I use the different colored wire rings. I have a bunch I had ordered with all the different colors. Each different breeding will get a different color which will be marked into my records. With all my young being mixed together I can tell the different breedings by their colored rings in this way I can compare the young from the different breedings with each other. Yes, it's a lot of work, but worth it in the end, keep good records and cull hard.
Dick