Since the term 'Swallow cm first time stories' is so unclear, I can't provide details. It might be a very unique or local concept that requires more background knowledge. It could be about a new discovery related to a Swallow - perhaps a species - and some measurement in centimeters during the first encounter, but again, this is just guessing.
As I have no information about what exactly 'Swallow cm first time stories' are, it's impossible to share details. It could be something very specific to a certain field or community, but without further clarification, there's nothing to be said about the details.