Fanaelialae
Legend
In my interpretation it requires both finding the pseudodragon and convincing him to join you, and casting the spell (otherwise p347 doesn't make a lot of sense).
The way I read p. 347 is that spellcasters who can cast find familiar will most likely have a familiar (as defined by the spell). A spellcaster might instead have a familiar as defined in the individual MM entries such as pseudodragon, etc.