I would say that if a manufacturer announces a date, the only thing it means is that the figure will likely be released within @ 4 months from that date. Release exactly on time is rare, and release any earlier is very rare (but not impossible).
To put it another way, I think legitimately accurate time estimates will be phrased as "fourth quarter 2014" with the understanding it could spill into the next Quarter. Anything more specific than that is just random guessing. As specific as "March 12" is likely absurd (or it comes from someone who has to put the item down on a specific Orders list like Diamond's, so they just guess an arbitrary date). As actual release gets closer, distributors and retailers may be given some more specific updates by the manufacturer which may or may not be reliable. The unpredictable complications of Asian release vs international customs etc means that any estimate would still be +/- 1 month even if we could calculate based on knowing the exact manufacture release date -- which we never do anyway.
Thinking you could have a reasonably precise 1/6 release date list, like eg for Comics, will drive you insane.
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