instruction: when was the first blood, venipuncture microbiology test done for patient 031-3355?
response: SELECT microlab.culturetakentime FROM microlab WHERE microlab.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '031-3355')) AND microlab.culturesite = 'blood, venipuncture' ORDER BY microlab.culturetakentime LIMIT 1