Hello Teresa Hangchi, thanks for your support. Since we need about 4 weeks to make this costume, so we are afraid they are unable to reach you before 7 December.
**if you order them now (about 4 weeks making costume time) and use the fastest shipping method (Premium Express, 3-6 days shipping time), it will reach you around 5 weeks after order is paid & confirmed.
*All shipping information (including methods, cost & estimated delivered date) will be shown in order page, before payment; you can pay extra cost to upgrade shipping method there.
*Please remember to mark down the date (you need it) in the order form when you order it. :)
For the costume size chart, please click "Size Chart" under the "Buy it now" button, we provide the size standard both in "cm" & "inch" standards.