How long after a breast reduction am I at risk for developing blood clots?

The risk of DVT can be as long as several weeks postop, with one study suggesting that most of the risk is at three months and after this period the chance of developing this complication drastically reduces as the patient moves forward to her recovery. 

Light exercise, particularly walking throughout the day, is a powerful tool in preventing or at least minimizing the risk of DVT.  Achieving one's optimal health and controlling certain medical conditions well in advance of the surgery can also make a huge difference. 

I hope that helps and good luck. 

in general blood clots are very rare after the kind of surgery that you had but being aware of the risks never hurts. I have seen presentations demonstrating blood clots  for even up to six weeks after surgery but generally by 10 days the risk is very small. Early ambulation is the best option and be sure to avoid getting the dehydrated.