eh. there's not really a true "break-in" period. if you're worried about it, then keep it down for a few days maybe even a week then let that bugger wang.
It won't sound the same after break in as it does initially. It will get to its final state more quickly is you just get on it from the beginning. If you're really worried about it hook it up to a home amp. Run it free air with about 10W on a 50hz sine wave overnight.