Elsewhere (later) on this board, Elaine (lost twin sister of Bobcat Goldthwaite!) rants against the deliberate naming of a child knowing you're going to use the child's middle name as its given name.
While Elaine manages to include something to offend about everyone in her tirade, I basically agree with the middle name-given name sentiment. I believe you should at least start out planning to first-name the kid whatever you're planning to call it. Things change later sometimes, but why institutionalize confusion from the start?