The earliest plausible time a legitimitate contender will announce a 2016 run?

[Matty]

When is the earliest it could reasonably happen? I know some folks have come forward and said they will make a "decision" in early 2015, but that doesn't mean they'll announce that early.

[BaconBacon96]

By legitimate contender I assume you mean no John Bolton's or the like. I've read that Ted Cruz and Bobby Jindal plan to announce as early as this December and Hillary might announce as early as January.

[Mr. Morden]

Define "legitimate contender" and define "announce a 2016 run".  Does launching an exploratory committee count?  Because if an exploratory committee counts, then the NY Times says that there's at least some chance that Clinton would start her exploratory committee before the end of this year:

https://uselectionatlas.org/FORUM/index.php?topic=164982.msg4335453#msg4335453

Bush was also saying at one point that he'd decide before the end of the year, though it sounds like that's softened to "end of this year or early 2015".  Based on recent reporting, it sounds like we might also get something early-ish (perhaps even November or December) from Bolton, Jindal, or Portman.  Though again, that's probably an exploratory committee.

But once you have an exploratory committee up and running, then you're acting exactly like a candidate.  The formal declaration of candidacy that follows that is little more than a formality.