I know everybody says you got 20 days to book the ceremony but it's not mentioned in AN Guide or AN Booklet.
If your application is successful and you are living in the UK, you will be invited to attend a citizenship ceremony. You will receive an invitation letter from the Home Office and this will confirm the local authority you should contact to arrange your ceremony. We expect you to arrange to attend a ceremony within 3 months of receiving your invitation otherwise it will expire and you will have to reapply for naturalisation and pay a further processing fee.
So my application was approved on the 2nd of April but I still haven't received the invitation letter from the Home Office. Is it fair to say that the clock hasn't started yet? I've underlined: 3 months from receiving the invitation and not 3 month from the approval date. Even if it's 20 days - does the clock start after you've received the letter? Surely there's no way for them to track these letters so how do they establish when the deadline ends?? What I'm trying to say is it possible that they're not that strict about it these deadlines...