score:1
The decision whether and for how long is made on arrival:
At the port-of-entry, a U.S. immigration officer of the Department of Homeland Security (DHS) decides whether to allow you to enter and how long you can stay for any particular visit, as part of the Admission process. Only the U.S. immigration officer has the authority to permit you to enter the United States.
Six months is the normal maximum but this may be extended Up to 6 months; maximum total amount of time permitted in B-1 status on any one trip is generally 1 year.
Leaving USA terminates the validity of the visa, where that is single entry, or utilises one of the allowed entries where multiple entry. Returning from the EU (after Christmas) is a further entry, the duration of which is again up to the immigration officer β and might be six months.