It just means that during this time the thermal paste is curing (the heat from the processor is doing this) so you may see slightly higher temps for the first week or two. After that your temps should be a bit cooler but it's not going to be by a large amount, maybe a couple degrees C. Not like a 10-20c difference or anything. So long as the thermal paste is applied correctly and everything is working and temps are good, just use your laptop. You won't have to do anything else while it's breaking in.