The crowd on 26th December

I am planning to go Shanghai on 22nd to 26th Dec. I want to visit Disneyland, however I am not sure if I should go on 23rd (after the day we landed) or on 26th Dec after Xmas. Because we want the most less crowd when we visit. I checked that school holidays for Shanghai is on 18th Jan onward but read that 26th Dec is also a boxing day. Please advise which date is the best should I go?