Blizzard has just announced the unlock schedule for the Blackrock Foundry raid! Normal and heroic modes open on February 3, with Mythic opening the following week on February 10. Raid finder begins to unlock with wing 1 on February 17, and you'll have to wait all the way until March 24 to kill Blackhand in wing 4. LFR will require a minimum item level of 635.
Keep in mind this doesn't mean patch 6.1 will be released on the same date. The @WarcraftDevs Twitter account has already told us that the two are not dependent.
Check out the full unlock schedule after the break.