Hello ISABELLE, the in-stock size costume is in our office right now, and can be shipped out directly after the order's confirmed.
If you order the in-stock size costume now and use the fastest shipping method (Premium Express, 3-6 days shipping time), it will reach you around 4-7 days after order's confirmed. n_n
*Please remember to mark down the date (you need it) in the order form when you order it. :)