when was the last time during their first hospital encounter that patient 17608 was prescribed a drug via subcut?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 17608 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) and prescriptions.route = 'subcut' order by prescriptions.startdate desc limit 1