Happy New Year!
Note: The decade ends Dec 31 2010 - just like the previous Millennium ended 31 Dec 2000 - seeing as there is no Year 0 in our calendar.
But you cold say Happy start of the '10s' if you wanted to 
Being a touch endantic is a consequence of age, I think.
The years 2010-2019, in terms of a historical using, will be considered the second decade of the 21st century (even though based upon the gregorian calendar technically, 2010 is part of the previous decade).
For instance (and assuming we are talking about the 20th century),
Roaring 20s = 1920-1929
The 60s = 1960-1969
Nontheless, whereever you want to call it, have a great 'decade'...
