When is the right time to try putting day old chicks under my broody?

[Oneacre Homestead]

I've got a brooder full of day old chicks and a broody outside
Who has been sitting on fake eggs for three weeks ... Should I wait for pre- dawn to try to give her some, or can I try now?

 

[StarLover21]

Do it ASAP while the chicks are still a day old.