Maybe try january 3 or 4, try 4:00pm or 6:00 pm for both of those dates you choose,
im not in charge of this current clan battle but im will just try to help you manage it...
also how large will the battle ground server be? because we need the server size to be above 12 and im not really sure if a server can go up to 18 people, but anyways its best to have 12 people for less lag