Yes, the Second Avenue Subway is opening on January 1st at noon, after a ceremonial New Year's Eve ride that has been decades in the making. But regular service actually won't start until the following week.
The MTA says, "Revenue service will begin at noon on January 1, when the first uptown Q Subway train to Second Avenue departs from the 57-7 Av station. Trains will run every six minutes during peak hours and will run from 6 a.m. to 10 p.m. for the rest of the first week. Overnight service will begin on Monday, January 9." (The NY Post headlines it, "Second Avenue Subway opening is delayed yet again.")
"The Second Avenue Subway is the most significant addition to our system in 50 years and will significantly reduce crowding on the Lexington Avenue line which currently serves more riders than the Chicago and Washington, D.C. subway systems combined," MTA CEO and Chairman Thomas Prendergast said in a statement.