The owner of a property is responsible for ensuring that rental dwellings have heating systems capable of maintaining a minimum of 68 degrees. There is no scheduled turn-on date for heating in multi-family units. This is considered an emergency in most circumstances and should be dispatched to DHCA immediately. See Section 26-(7) (e) (3) of Chapter 26, Housing and Building and Maintenance Standards on the attached link for the Code reference. 
To file a complaint regarding no heat in a rental dwelling unit,  please see the topic entitled  "HOUSING COMPLAINTS"  or click on the second link below.