Got my letter yesterday too - for 18/12.
I'm checking with Nurse Debbie, but I reckon it won't be a drama, as they always need blood, and they particularly need it over the Xmas culling season on the roads.
My only concern is for James, who would be 1 week early.
(Strangely, Debbie initially told me Dec/3 was the eligibility date, which is why I confirmed 17/12. Anyway...)