I'm fine with either idea, my only objection against the introductions is that I'd prefer not to get bogged down early in the morass of introducing each character's particular proclivities (something that usually happens with introductions and takes a long time). Rather, I think starting straight off with the assumed knowledge that each character is a part of the clan and has a basic understanding of its rules means that we can get to the group building dynamic all that much quicker without focusing too much on each character individually. 

Not sure if that made complete sense but tl;dr start with a mission and team building, character introductions can occur naturally as we play.