It is commonly held that a priest can offer a "first blessing" for the entire first year as a new priest. Sometimes it is said that there is a plenary indulgence attached to receiving a blessing from a priest within the first year after his ordination to the priesthood. I have been looking for the origin and basis of this tradition, but haven't found much. Maybe one or another of my readers know something about this.
The two questions I have are: first, is the notion that there is something special attached to a priest's blessing within his first year of priesthood based on (1) a pious tradition, (2) some liturgical tradition, or (3) a determination made by some pope?
Second, what is that "something special" that is attached to the blessing of a new priest within the first year of ordination (if not an indulgence)?