Per my social security statement:
2002 2,029 (age 15)
2003 2,445
2004 2,194
2005 52
2006 1,239
2007 1,697
2008 3,268 (finished college)
2009 4,057
2010 32,744
2011 3,375
2012 115,803 (finished graduate school, started work in March)
2013 153,950
2014 186,452
2015 269,321 (changed jobs)
2016 ~ 290K (I expect, we'll see)
ETA: I didn't answer your question. About five years. Realistically, if I counted based on full-year numbers, I will double it in 2017, having started my real career in 2012. I think the hardest part for me was the 2012 foot in the door, and, to a lesser extent, the move last year. I don't expect huge growth now, but I don't really need it.