how many days has it been since patient 31482 first was prescribed oseltamivir on the current hospital encounter?
select 1 * ( strftime('%j',current_time) - strftime('%j',prescriptions.startdate) ) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 31482 and admissions.dischtime is null ) and prescriptions.drug = 'oseltamivir' order by prescriptions.startdate asc limit 1