I assume you mean release, as often the code can update several times daily and these are available as dev builds.
The "correct" answer is probably best translated as "when it gets here".
A rough estimate for a release however, would place it in January ~ February-ish (2013, obviously), as the release cycle seems to revolve every 3 ~ 4 months, and 3.12 made it out of the workshop on October 6th 2012. It is not a schedule one can set their watch to, however.
Generally speaking, the bleeding edge code is perfectly safe, and even if you do encounter bugs you can always revert to a release build with a trivial amount of effort. If for some reason you would prefer to run only release builds, then closer to the time of release you may expect an "RC" (Release Candidate) build which may suit you better. Keep an eye out in the forums or the mailing lists for notification of upcoming releases and/or release candidate builds.
[Saint]