Broody Hen with no Rooster

[NoAcres]

I have a buff orpington that has gone broody in the last couple of days. We do want more chicks, but my question is, should I get fertile eggs to sneak under her or 1 day old chicks? Do I need to wait the full 21 days to put live chicks in with her? Just wondering if she has her own time clock so to say and would know that the chicks weren't hers since it's only been a couple of days since she started brooding

 

[ChickenCanoe]

You never know and you could do it either way. If you use fertile eggs, get them sooner rather than later.
If going with day olds, there's no hurry but usually I feel safe after 2 weeks of being broody.