Music starts early

Sorry to disagree but LP groove echo, not tape print-through, gets my vote as the most commonly perceived occurence by the home listener. Like many, for years I thought groove echo was a playback induced event. It's not. Groove echo is an artifact created in the LP cutting and plating process, independent of the master tape. See Bob Ludwig's explanation:

http://members.tripod.com/~Vinylville/groove-echo.html

Certainly tape print through pre-echo exists and causes problems, but I doubt it's the one that we're most accustomed to hearing.

Lugnut, the echo isn't coming from the stylus improperly picking up the adjacent groove, the stylus is tracking the info that the lacquering and metal mastering process created and left behind. As you note the entire groove echoes the one next to it. The of necessity soft nature of the lacquer encourages this. Like a sound echo you make with your voice this one is made by the cutting head deforming its surrounding environment, however slightly. The blank lead in grooves are especially affected because they have no signal cut into them to override the echo. As noted in the Ludwig article, the longer the lacquer sits before making the metal master the more the echo cures into the adjacent grooves.