Brian Johnson (Eagles QB coach) is the only coach still coaching who has been publicly linked to the job. Personally I never thought he was a leading candidate, but that's more opinion than anything else, so could be wrong. He's a Mullen guy with SEC experience, well thought off and respected, and if he as the guy, would undoubtedly come with the stamp of approval from a number of former Saban staffers who work with him currently in Philly. (Johnson was also an outside candidate for the auburn HC job after Harsin was canned)
All that aside, there is no magic date other than Saban is highly unlikely to name a new OC until/before O'Brien accepts another job. Word will likely leak out, and the guy may already be working to some degree, but there's no reason to expect definitive word until the O'Brien domino falls. O'Brien may accept a spot with the Patriots, he may not. He has options.
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