what time did patient 31300 first had the minimum tacrofk value until 11/2103?
select labevents.charttime from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 31300 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'tacrofk' ) and strftime('%y-%m',labevents.charttime) <= '2103-11' order by labevents.valuenum asc, labevents.charttime asc limit 1