9/23 is ok for me if it is after 9pm, but it might be hard for everyone else because they live farther away... the night of the 13th and all day on the 14th are ok for me also.
My Mid-Year Conference will be November 25th (火)〜November 27th(木). Monday is a Holiday and I can take that Friday off, so I can come early (~21st) or stay late (~December 1st).