when did patient 32168 have a hemoglobin test for the first time on their first hospital visit?
select labevents.charttime from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'hemoglobin' ) and labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 32168 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) order by labevents.charttime asc limit 1