i dotn have answer to the Q.. but one clarification: it is not "nationwide".. its just northern part of china... one thing i envy of living in north china.. here in central china.. temps go down negative at night.. and we switchon aircon etc.. and get a bill of >1000 pm.. still most part of apartment is damn cold...envy u guys over there...

October 20th in Shenyang.

I just got to Beijing, so I am not certain, but my "Apartment Regulations" say that central heating runs from November 15th to March 15th.  I don't know if that is correct and if it varies by region, but after doing an Internet search, it sounds like unless a decision by the government is made to turn it on earlier, November 15th will be when central heating gets turned on for Beijing.

http://english.people.com.cn/90001/90776/90882/7163232.html

Never in Shenzhen  ..................it is 27 degrees here now, move to Shenzhen

 It should turn on the first week of November.

The heat went on in Harbin about ten days ago.