Troubles to book my ceremony at local council

[alexdigime]

Hi, could anyone share your recent experience of how long it takes for your Council to receive a
Citizenship certificate from Home Office that you could be able to book your ceremony?
I got a "Citizenship ceremony invitation" email on 20th August 2021 where I got this:
Please wait one working days after receiving this approval before you try to book, as it may take a
few days for documentation to arrive at the local authority.

But when I login to my my council website I always get Home Office reference not found.

My local council is Newham London. My reference number looks like this: XXXX-XXXX-XXXX-XXXX
(16 digits)

I tried to call to UK Visas and Immigration contact centre 0300 790 6268 (option 2 then option 1)
and also my Newham council 020 8430 2000 but there is no option for me to speak with an
agent. The answering machine only have one option - check online…. or nothing…

What will happen if it will take more than 21 days?