I think another week-I have to check the calendar. We had a successful incubator hatch with 12 Lavender Orpingtons out of 24. That is a good hatch for that breed.
Should always be 21 days from the first day of brooding. Occasionally there are eggs that are laid in the clutch after that day. Those will hatch later if allowed to stay, but mom may well abandon the nest with her chicks before that time. The mom's 'breather' is built into proper care of the developing eggs.
I have always marked the eggs in the clutch to be sure I can find and remove any late comers.
Those are sweet HPQ, Black Australorps are one of my favorites, and she looks like a good mommy.
I currently have 6 broodies, out of 14 hens.
2 of those are banties and one of those is my special pet, so I ignore them and let them set.
The other 4 are going on their second or third broody session this summer and aren't responding to my breaking efforts.
It wouldn't be too tragic if I actually had fertile eggs (I think my bantam Cochin rooster is a tad short) or room for more chickens, but I don't and I don't.