Exact day to apply for Citizenship

Hi
I obtained my ILR on the 27/12/2023

Does that mean I can apply for Citizenship on the 27/12/2024 or the 28th?

Also, can I submit the application earlier than the 27/12/2024 but do the biometrics appointment on or after the 27th?

Thanks

Yes you can apply on 27th or anytime after this date.

However, you cannot apply before the 27th - not being an immigration application there's no apply early concession. The biometrics date is not relevant here - do it within 40 days after the 27th.