when did patient 63700 enter the hospital via clinic referral/premature for the first time until 1 year ago?
select admissions.admittime from admissions where admissions.subject_id = 63700 and admissions.admission_location = 'clinic referral/premature' and datetime(admissions.admittime) <= datetime(current_time,'-1 year') order by admissions.admittime asc limit 1