If you're jb you cannot update OTA at all.
It will just error out.
If you want to get to 6.1.2 you will have to plug it to iTunes and hit restore.
Not update, that won't work either and you will just get stuck at the apple logo.
OTA updates were knocked out when you jailbroke your phone. It came in one of the evasion untether updates in Cydia. Your only option is to physically plug your iPhone in to a computer and update through iTunes.