The expectation was to have the change in place by Jan 1 to address new federal laws but the timing appears not to be exact. At the same time it may have been but since we don't know when cars were specifically built we have no way that I know of knowing. Change was only to the drivers side inner fender lip
About 6 months ago I went through and documented what I had related to the change over and found fenders dated as Jan 18 didn't have the crumple zone modifications and the earliest date on fenders with the modification were dated Jan 14 suggesting that that four days was the transition period to full changeover of all the working machines and dies at the stamping plant
Hope this helps