I think it's only 30-40% of the set of eggs will be a frizzle. It's not a high number at all, it could be less too. They may have the frizzle gene, but over half do not hatch out with the frizzling feathers. The frizzling is all different too, some are more curly then others. Your really taking a chance frizzling hatching eggs. There is no guarantee.
I have a frizzle cochin roo with a variety of hens. I gathered up the eggs to hatch and ended up with maybe 30% frizzeled and the rest are all smooth feathered. Most I could tell by a week of age, some slow developers I couldn't tell until closer to two weeks of age. Their first feathers will be curved like eyelashes if they will be frizzeled.
Thank you everyone for responding. I know or knew the frizzle gene was like getting a blond with blue eyes, not a dominate gene. I hatched 10 of the polish that had been breed with a frizzle, and had promised a couple of the chicks to friends, so I didn't want to give them out before I could tell if there was a frizzled one or not. It was my first time incubating and had pretty good success, so I'm happy with what I ended up with. Again, thanks to everyone who responded, I appreciate it!