when was the first laboratory test patient 14458 received in 09/2104?
select labevents.charttime from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 14458 ) and strftime('%y-%m',labevents.charttime) = '2104-09' order by labevents.charttime asc limit 1