for the first time, what test was given to patient 42829 in this month?
select d_labitems.label from d_labitems where d_labitems.itemid in ( select labevents.itemid from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 42829 ) and datetime(labevents.charttime,'start of month') = datetime(current_time,'start of month','-0 month') order by labevents.charttime asc limit 1 )