As per latest notification of HUDA which is available on its website, the construction needs to be completed within 15 years from the date of offer of possession.  However, plots by licensed colonies like South City-1, Greenwoods City, etc. by private builders are not covered by this restrictions.  In any case, it cannot be less than the 15 years time-frame.  In your case, you must, if it is presumed that it will cover your plot too, completed construction on your plot by September 2018.  I have a plot in Greenwoods City and got the possession in Aug. 1997.  I will have to complete construction by August 2012.  But I still feel our plots do not come under HUDA policy.  HUDA will have to take out another notification covering these plots.  

Just to be curious, how come you bought the plot from Unitech so late in South City-1?  Did they have any plot left there?  What was the rate?

As per latest notification of HUDA which is available on its website, the construction needs to be completed within 15 years from the date of offer of possession.  However, plots by licensed colonies like South City-1, Greenwoods City, etc. by private builders are not covered by this restrictions.  In any case, it cannot be less than the 15 years time-frame.  In your case, you must, if it is presumed that it will cover your plot too, completed construction on your plot by September 2018.  I have a plot in Greenwoods City and got the possession in Aug. 1997.  I will have to complete construction by August 2012.  But I still feel our plots do not come under HUDA policy.  HUDA will have to take out another notification covering these plots.  

Just to be curious, how come you bought the plot from Unitech so late in South City-1?  Did they have any plot left there?  What was the rate?