Actually, if I recall those Macs were taken directly off the production assembly line and not given to the team until the Mac shipped, which was not until late January. Until confirmed one way or the other, I would not presume that these were taken off the assembly line earlier than they were needed, i.e. unlikely it was over a month earlier. Since they were fully boxed, keep in mind, the software golden masters were not prepared until late January, so while there were several weeks of Macs sitting around, they had yet to be packaged. This doesn't preclude them from being packaged without a complete set of software, but somehow I don't think Jobs would have done that.

Also, I believe the Macs went into production at least by the second week of December. In any event it is unlikely they went into production between Christmas and New Years, because if there were any problems, too many support businesses would not have been available to assist. So logically speaking, the Mac had to go into production at least the week before Christmas, and probably two weeks before for safety due to the holiday, if not earlier.

So Anonymous Freak has properly qualified his assertion of the first production model known.