Firstly – check when your end of year date is!
Many charities follow a calendar year, so start afresh on 1st January and close the year on 31st December. But others use the date they were registered, or some other date agreed with the Charity Commission.
Whoever is going to take your accounts to check and/or combine with the larger charities will have a deadline for you. If you are the person doing the full charitable accounts, then create and work towards a deadline after your fiscal end of year.
As you work through the year keep that date in mind. Ideally you start getting ready to close down the accounts as you start the year’s cashbook and records at the beginning of the year and then maintain good monthly records, so that when the end of the year approaches there are a few bits to tidy up but nothing major.
For example: you should be thinking more “Must chase Jane for that last expenses receipt she’s not sent in.” than “hmm receipts yeah I had a pile around here somewhere…”.