I would suggest you break them in as you broke in the car when it was new. New gears need heat cycling in increasing increments of load, so going by the break in for a new car is a good guide. Once you reach about 1000 miles to 1500 miles do a fluid change because by that time, you should have put full load on them many times (ie, WOT running to to redline through several gears). An inspection of the oil fluid and the stuff on the magnet will tell you a story as to how they're doing.