"Break in" is unnecessary with current plasmas. Like all displays, they will gradually dim over time. And during the first few hundred hours, they will dim proportionally the most (as in, they will drop several lumens in brightness during the first few hundred hours and then be quite stable and slow to dim after that). So if you are paying for a professional calibration, it is worth your while to wait for a few hundred hours of use so that the settings will not need to be changed.
But the whole "break in" process of keeping the set dim and displaying nothing but uniform "break in patterns" is unnecessary. Burn-in virtually never happens anymore. Image retention, on the other hand, is still entirely possible. But the "after-image" disappears on its own after just a few minutes.
So feel free to go ahead and watch movies, TV and play games
I wouldn't recommend Vivid Mode, simply because it is an awful picture mode! Just do a simple THX Optimizer calibration to start. And then, after a few hundred hours of use, go ahead and do a more in-depth calibration or bring in the ISF technician