when was the first time that patient 31696 has been prescribed medication via td route in 07/last year?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 31696 ) and prescriptions.route = 'td' and datetime(prescriptions.startdate,'start of year') = datetime(current_time,'start of year','-1 year') and strftime('%m',prescriptions.startdate) = '07' order by prescriptions.startdate asc limit 1