Nearly always fabric first, in fact I just recently bought my first ever'paid for pattern' (a bargello) and pulled some from my stash but ordered the rest. :-D The exception is that I love making the One Block Wonder kaleidoscope quilts and those require a certain type and amount of fabric, so I guess you could say that there, the pattern dictates the fabric. :-D
I don't think a big stash is a big problem either - it'll all get used someday - so long as I live to be about 200! :mrgreen:
And as someone on here once said, 'she who dies with the most fabric, wins!' Right?! :lol: