Before, prior to. There is no difference between these two except length and a certain affectedness on the part of 'prior to.' To paraphrase Bernstein, if you would use 'posterior to' instead of 'after,' then by all means use 'prior to' instead of 'before.
Bill Bryson"Croissant": However you choose to pronounce it at home, it is perhaps worth nothing that outside the United States, the closer you can come to saying "kwass-ohn," the sooner you can expect to be presented with one.
Bill BrysonMost of the time I am sunk in thought, but at some point on each walk there comes a moment when I look up and notice, with a kind of first-time astonishment, the amazing complex delicacy of the words, the casual ease with which elemental things come together to form a composition that isโwhatever the season, wherever I put my besotted gazeโperfect.
Bill BrysonAt the foot of the mountain, the park ended and suddenly all was squalor again. I was once more struck by this strange compartmentalization that goes on in America -- a belief that no commercial activities must be allowed inside the park, but permitting unrestrained development outside, even though the landscape there may be just as outstanding. America has never quite grasped that you can live in a place without making it ugly, that beauty doesn't have to be confined behind fences, as if a national park were a sort of zoo for nature.
Bill Bryson