December 15th and 16th
January 15th and 16th

Wikitravel - Setagaya
http://wikitravel.org/en/Tokyo/Shimokitazawa
Official site
http://www.tokyo-cci.or.jp/setagaya/tiikijouhou/boroichi/index.html
Other good site
http://www.setagaya-line.com/trip/boroichi/

go to Google Maps