when was the first time patient 2425 had a lab test, until 35 months ago?
select labevents.charttime from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 2425 ) and datetime(labevents.charttime) <= datetime(current_time,'-35 month') order by labevents.charttime asc limit 1