A wee bit more information...
I just called my USDA vet location, here:
USDA, APHIS, VS
1598 Whitehall Road
Suite A
Annapolis, MD 21409
Hours of Operation: Monday - Friday 8:00 am - 4:30 pm Eastern
Hours for Health Certificate Endorsement:
Monday - Friday 9:00am - 11:00 am and 1:00pm - 3:00 pm (appointment required)
Office Email: VSMD@aphis.usda.gov
Telephone Numbers:
Main Phone: (410) 349-9708 & (301) 261-8072
Fax: (301) 261-8113
The woman I spoke with told me it is actually better if you do the USDA step after the 6-month interval. And also, another piece I didn't know, but others might... There is some 7001 form that you must get from the vet. It's the piece required by the airline to certify that the pet is healthy enough to travel. I knew that such a statement was required, but I didn't know that there was a specific form that had to be used! She said that all vets usually have it, and it's what's required "to get your pet out of the US."
Hope these little bits are helping others get their beloved fur-babies safely to England!
~Teddy