They are still signing 6.1.2 so if your going to do it, then I suggest you do it right now. I believe after 24 hours Apple may no longer sign for 6.1.2. I verified with redsn0w that the appticket signing is still valid at this time.
Restore in DFU mode and make sure you have the Apple Official Firmware for 6.1.2 located in this section of the forum.