Don't panic yet. It's not that unusual for eggs to hatch a day or even two full days early or late, even under a broody hen. Sometimes my broody hens are on time but about half the time they are a full two days early. Other flocks are consistently late. There are different things that cause that. I know it doesn't do any good to say not to worry, you are going to no matter what any of us say. Just be patient and don't do anything silly.
Are you counting the days correctly? That's a common mistake on here. It takes 24 hours for an egg to have one day's worth of incubation. Logic says to say "one" when you first put the eggs under the broody but it doesn't work that way, you say "one" 24 hours later. An easy way to check your counting is the day of the week you set them is the day of the week the 21 days are up. If you set them on a Tuesday, the 21 days are up on a Tuesday. But they can still be early or late.
Keep us updated on progress. Here's pulling for you. And no, there is nothing you can change at this point that will help, but bothering the hen is not a way to help her.
