How do you properly break-in a pair of speakers?

One trick, which works better with monitors, is to place them face to face and wire one out of phase with the other. Throw a blanket over the whole thing and turn up the volume until your spouse complains, then back it off a little.

Just throw in a CD and let it go!

Various full scale music will work fine (classical with organ is good). I do not play new speakers loud @ first (if the sound becomes compressed or dry, then this is too loud, IMO, plus who wants to listen to this).

Most of the new speakers that I have owned loosened up in the first 100 hours (as far as increasing the volume goes), so try to be patient if you enjoy listening @ higher levels.

I don't know if a fairly high volume will actually damage the drivers in the beginning, but I try to treat them as I would a new automobile engine and this has worked well for me.

What speakers did you purchase? Could be that someone will be able to give you a time line based on experience.