The lipo battery will reach its full potential after 5-10 cycles of normal use. No break-in needed but you want to let it cool down before you charge it. Balancing is more important afterward though.
The brush motor can be broken in by attaching a single D battery and dunk the motor in the water while running. People believe that doing so will break-in the motor because the brush will seat well on the amateur shaft as the evident of carbon dust in the water after the session.