I thought we all agreed that this whole "hoopla" about break-in was a thing of the past. Meaning, unless you put the engine together in your garage with different parts, tolerances, etc., with major manufacturers these days the engine is pretty much "broken-in" as it's driven off the assembly line as soon thereafter. As far as metal particles...that what the filter's for (I would hope). Unless a manufacturer suggests NOT to change an oil until x mi., I would assume you could change it any time you like eg. the day after you buy it - synthetic or otherwise.
As far as my experience with European cars, they generally recommend to change the oil at the first 1-2k mi. mark. Not because you're NOT permitted to change it earlier, but because this IS earlier than the 7-8k normal recommended change interval since it can be assumed that the oil will be 'dirtier' at this shorter change interval as the engine is new. Likewise, such an engine should be driven at gradual speeds because "sudden" break-in doesn't occur...breakage does. So again, unless otherwise stated, the speeds during this time should be in the "lower" rev. ranges at speeds below 100mph.