Exchange of order for pass

Hi,

I'm going to Japan in December and I have a question about the JR Pass. Firstly, the ticket which most fits to my need is the 7-day one, since I arrive in December 11th and leave in Dec. 18th.
I land in Haneda airport in December 11th at 10.20 pm. I noted that the JR office in the airport will be closed. Thus, I guess I won't be able to use the JR Pass to go to the city in the first night, right?

Please let me know if I have another alternative to use the pass as soon as I get Japan. Otherwise I will choose the starting date as December 12th.

Thanks