That's what I think too. I now have 4 hens with chicks, and they had just started laying beofre going broody. I only have trouble with one, concerning how she takes care of the chicks. But she is really fat, and whenever we try to let her free range with her chicks, she runs off and forgets about them when she sees food being tossed out.
I don't believe she would necessarily leave the eggs on day 25. It really just depends on the hen. You could go ahead and give them to her, and have your bator ready if she does leave. My dad had a hen that sat the nest for 6 weeks,(all her eggs were no good), and didn't even leave when she had no eggs left. We finally went and got her some day old chicks from a guy in town.