Purchase train ticket from Shanghai to Hung Hom

We will be on SH on 17 January 2016 and intend to travel on the 18 January from SH to Hung Hom.

As we will be in Hong Kong on the 6 January. Can we purchase the SH to Hung Hom sector for Delux soft sleeper in Hung Hom station instead of last minute purchase when we are in SH on the 17 January 2016.