I haven't seen a break in precedure in the factory manuals I have. Most companies that build will reccomend a precedure such as this.
"For the first 5 hours do not run a constant RPM. Vary the RPM's every 5 minutes or so. Do not exceed 75% throttle for the first 5 hours. Shift into forward and reverse a minimum of 10 times in the first 5 hours. For hours 5-10 you should do short runs at full throttle. After 10 hours normal operation can resume. Change the gear lube between 10 and 20 hours"
Just don't beat it to death and allow the gears to seat in and it should last a whild. I hope this helps