I have 2 bantam black orpingtons that started laying about 6 weeks ago. Most of the eggs I crack are fertilized. I also have 2 10 month old gold sexlinks. I don't usually break their eggs because those are the ones I sell. But, today I opened 2. 1 was definitely fertilized & one was hard to tell. So, I gathered up 4 big eggs & 5 little eggs & fired up the bator. Now I'm nervous having them in together. Do the bantams take 21 days too? Should I add them later so that lock down is at the same time?