WordNet sense 1 (badly timed):

ill-timed, unseasonable, wrong

WordNet sense 2 (not opportune):

inopportune

WordNet sense 3 (uncommonly early or before the expected time):

premature

WordNet sense 4 (at or near the beginning of a period of time or course of events or before the usual or expected time):

early

WordNet sense 5 (too soon; in a premature manner):

prematurely