pioneer (adjective) pioneer: early, first
Sinonime: be apprehensive of, be curious, be dubious, be in a quandary, be puzzled, be uncertain, be undetermined, call in question, challenge, demur, disbelieve, discredit, dispute, distrust, fear, fluctuate, give no credence, harbor suspicion, have one's doubts, have qualms, hesitate, imagine, impugn, insinuate, misgive, mistrust, not buy, query,
question, read differently, scruple, shilly-shally, skepticize, smell a rat, surmise, suspect, take dim view of, vacillate, waver,
wonder, wonder at
Antonime: following,
last,
late,
later