https://wiki.debian.org/DebianJessie
2012-07-27: Distribution codename announced
2013-05-04: Wheezy released, development on Jessie started
2014-11-05: Jessie freeze Debian 8.0 "Jessie" is frozen
2015-01-26: Jessie installer RC1 released
Debian Wheezy Life cycle
2010-09-03: Distribution codename announced
2011-02-06: Squeeze released, development on Wheezy started
2013-01-23: Freeze policy update (no more translation updates), see announcement
2013-02-17: Wheezy releases release candidate 1 (RC1) installer, see announcement
2013-04-27: Wheezy releases release candidate 2 (RC2) installer, see announcement
2013-05-02: Wheezy releases release candidate 3 (RC3) installer, see announcement
2013-05-04: Initial release: 7.0.0 (press release).
Wheezy 從 RC1->Release 約花2.5個月, Jessie 應該也是差不多的時間了
另外 9 & 10 的代號如下
Debian 9 - Stretch 應該是取自玩具總動員
Debian 10 - Buster 應該是取自小姐與流氓