when was the first time patient 42757 was prescribed famotidine and gabapentin in 10/2102 at the same time?
select t1.startdate from ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'famotidine' and admissions.subject_id = 42757 and strftime('%y-%m',prescriptions.startdate) = '2102-10' ) as t1 join ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'gabapentin' and admissions.subject_id = 42757 and strftime('%y-%m',prescriptions.startdate) = '2102-10' ) as t2 on t1.subject_id = t2.subject_id where datetime(t1.startdate) = datetime(t2.startdate) order by t1.startdate asc limit 1